I want a boost mobile plan but I dont like the phone where can I buy a phone that will work for the frequency?

You can try a Nextel or Sprint handset.  They work on the same network but to get a different boost mobile phone you can go online at http://www.boostmobile.com.  On the website there is a store locator where you are able to type in your zip code and it will bring up the stores that are the closest to you that sell boost mobile products.  You can also order a new phone right off the website. 
Boost mobile does have a new phone coming out in a couple weeks that is a slider.  It looks really cool.  This phone has a couple new features that the other phones don't offer.  You can also purchase a used phone and purchase a starter kit with new SIM card and they can set you up that way as well.
Another thing about Boost Mobile handsets, most of them have the Walkie Talkie feature on them, so instead of calling all of the time, you are able to chirp as well.