A lot of people will buy a pair of shoes, and will absolutely fall in love with them. They think they are the greatest thing going. The next time they go to the store, they get distracted by a glitzier pair of shoes, or they find some shoes that are cheaper, or the model that they like is out of stock. Instead, they purchase something else, which works out all right for them but are not nearly as good as the ones they went to buy in the first place.
When you find shoes that you like, you should always try to keep a pair on hand. Something that works for you will normally keep working for you. Barring an injury such as plantar fascitis which changes the shape of your foot, or a change in training habits as you become more fit and more competitive, you should try to keep at least one pair of shoes in your rotation as the ones that you really love wearing. Having a second type of shoe is good as well, but if you have something that you like you should spend most of your money on those shoes. An extra $20 can keep you on the roads sometimes. That being said, shoes that cost $20 less might also be the perfect shoe for you; do not judge the shoes based on price alone.
All through high school, I used Saucony Grid Shadow running shoes. When I got to college, those shoes were just too heavy for the kind of mileage that I was doing and I discovered the Asics 2040 trainers. My sophomore year, they had a really good sale on them so I bought four pairs, which lasted me for quite a while as I used all of them in rotation at the same time. When I find shoes that I like, I stick with them. These days, my mainstay shoes have been the Asics DS Trainers and the 2100s. I am picking up some Nike shoes tomorrow that I got through my team sponsorship to try out, but they are going into rotation with shoes that I know work well for me.
Be aware that sometimes styles can change from one model to the next. My wife needs to use the Asics Gel-Kayanos due to a foot problem that she has, but from one model to the next they had changed the way that the shoe is put together and it made her problem worse rather than helping her. The newest model seems to have fixed that problem, but it can be hard to find the model that you really like with all of the constant “improvements” that shoe companies feel like they have to make. Make sure that you do not jump straight into a new model and buy as many pairs as they have. First, shoes only have a shelf life of a few years before the rubber begins to break down, so you don’t want them sitting around for a long time. And second, you need to make sure that the new model still works for you.