When it comes to budget, every runner will have different opinions about how much money you need to/should spend on gear, but in my experience a little bit of investment goes a long way and sometimes spending a little bit more in the beginning can make it quite a bit easier to get the most out of the sport.
For some people, spending more on shoes is a must, especially for runners with tendency toward injuries. For others, investing in a quality pair of comfortable, wireless earbuds is key to enjoying themselves on their runs. The best way to find out exactly what will make running regularly an achievable goal for you is to get out there and start running. The more time you spend actually logging miles, the better idea you'll have of what gear is worth the splurge.
Obviously shoes top the list of running essentials. However it might surprise you to hear that you don't need to go out and buy the most expensive running shoes you can find. I recommend being honest with yourself about how much you plan on running to start out with, and what type of surfaces you plan on logging the majority of your miles. Then go to a local running store with knowledgeable staff and ask for their help in finding the best running shoe for your needs. Plan on spending anywhere from $60-$120 for one pair of quality running shoes. If you live in Alaska, I can personally recommend Skinny Raven Sports in Anchorage and Active Soles in Palmer.
If you are a more experienced runner with plans to log an equal amount of miles on pavement and trails, I would suggest investing in a quality pair of trail-running shoes and a separate pair of road-running shoes. Every runner is different and will have certain physical issues they might be working around in regards to choosing the best shoe to fit their needs. Some might prefer more supportive shoes while others might be looking for a more minimal shoe. I'm in the minimalist group and prefer to run in shoes with less cushion and support. My feet are very 'claustrophobic' and so thick, restrictive material on the upper part of the shoe is definitely a no-go for me.
I run in Nike Free 4.0 Flyknits and Brooks Cascadia 9s and am very happy with both pairs of shoes. If the Brooks had the flyknit fabric on the upper they would be even better, but for trail running the heavier fabric on the upper doesn't bother me as much as it tends to when I'm running on the road or paved trails.
#2 SPORTS BRA
Being comfortable while running is pretty important when it comes to enjoying yourself and being motivated to run regularly. A huge part of being comfortable when you're a women is finding a bra that fits well, does it's job and looks good while doing it.
I used to love the Nike Pro Classic sports bra, and I still do for cross-training and very short runs. But as I've increased mileage and since breastfeeding two children, I've found that chafing has become more of an issue with this bra. I need individual support for each breast, as well as seamless cups. There are so many options out there for different chest sizes, but I've found that Moving Comfort bras are an industry standard for support and comfort.
My very favorite sports bra for running is the Moving Comfort Fineform A/B. I love the way it looks first of all, and it's surprisingly supportive for how strappy it is. I actually wear a 34-C and have found that the size medium A/B works better for me than the C/D version, so I definitely recommend trying both on if you've got a smaller band size.
#3 Fitness Tracker with GPS
With smart phone technology being what it is these days, I know many people use apps on their phones for tracking their runs. I used to do the same thing, until I just couldn't stand it anymore. Waiting for the app to load, waiting for my run to actually begin, inaccurate speed and distance, issues with bad reception, the list goes on, and I was just over it.
To me, it's well worth it to invest $100-$250 in a watch that's specifically made for runners, with it's own GPS capabilities so that you can leave your phone in the car. Personally I would steer clear of 'activity trackers' that focus more on tracking steps, and find a fitness tracker that is geared towards runners. I use the Garmin Forerunner 220 and love it. Knowing your pace is a huge part of training, so if you want to improve your times during races, having a watch like this is key.
#4 FOAM ROLLER
Casual runners are often pretty neglectful about self-care, i.e. stretching or cross training, which can lead to injury pretty quickly. Foam rolling has been a complete game-changer for me in regards to recovery after a difficult run or race. I foam roll in the morning and at night before bed in addition to before and after every run I go on. Any time I'm feeling tight or stiff, I foam roll.
I recommend getting a wider roller so that it's easier to get the hang of rolling. We have a long one we keep at home as well as two smaller ones that are more portable. Here is a great introduction to foam rolling, and REI has a pretty good selection of foam rollers (I always love an excuse to rack up that dividend).
#5 BODY GLIDE
Any time I run over four miles in shorts, I run the risk of chafing my inner-thighs. It's been over 70 nearly all summer, so I've been running in shorts pretty much every day. As a result, body glide has become my best friend. This stuff is amazing, when you put it on, you don't feel like it's going to do anything, but I've never chaffed while using it, even on runs over 13 miles in hot, sweaty conditions. It also works great on your feet and where ever seams might rub sensitive skin raw. Probably the best six dollars you'll ever spend as an outdoor runner.
In addition to these five items, I never leave my house without a few other items. A tiny thong and packable shorts live in my purse at all times - since having kids it's like a game to see how long it will take into my run before I pee, especially when trail running. Whether it's a little leak or my whole bladder (gross, I know, but trying to be honest here!) I nearly always need a clothes change if I'm going to be out in public or ride in a car. I know some women who haven't had children struggle with this, too.
I also always run with a small can of bear spray. The mace they make for personal protection isn't quite enough, at least for me since I run outside in pretty rural neighborhoods or trails in the middle of nowhere 95% of the time. Also if you are running trails that have low visibility, please run with the can in your hand. If you come around a corner and there's a bear 3 feet away, it's probably not going to do much good in a pocket of your stroller or even in a pocket on your running belt.
If there's something I didn't include that you think should have been on the list, please add your advice in the comments. Also if you have any questions, feel free to ask, I'm an open book. Happy Running!