ok i totally got this! finally a question i can answer woohoo!! the first question you should ask is how high is the arch in your foot, based off that answer a couple of choices are
high arch-
Nike free run around $100
(i have an extremely high arch in my foot and this is what i wear love them)
high to mid arch-
underarmour micro G (a cross trainer that you can run in) or
spine both around $80-$90
low arch-
Reebok realflex (completely lightweight and offers extra heel cushion)i have a pair and can't wear them because they kill my feet due to my arch, but if you have no arch their perfect, also you can find these on sale everywhere anywhere from $45-80
other good running shoes include
asics- several different styles(also styles for tennis), but good running ones cost around $140
brooks- really all they do is running shoes and this is what the hard core 5 mile a day runners come in my store looking for but their around $140- $160
New Balance- in my store i only have one pair of new balance but i hear really good things about them, namely what was said on here, that they last a long time. i know they make really good walking shoes, but since i haven't tried any on i can't say about what the arch is like.
i totally feel like I'm trying to sell something here, but if you can find a Hibbett sports near you most of them are fantastic when i comes to sizing your foot and doing an arch test and then offering recommendations. at least my staff is

hope this helps!