Boost mobile blackberry???????

[Lady A]

hey everyone...i just want to know if i cn use the boost blackberry on the 50 dollar plan or if i hv to use it on the 60 dollar one......the thing is that i hv a rumor touch with virgin mobile and i really like this phone plus the monthly plan is cheap however, it wont get very good signal in my room which i hate since i usually talk on the phone on the nights so i have to either go to the living room or deal with all the drop calls....this only happens in my room so it sucks.............well the thing is that this girl wants to trade for a bb for boost.......ive had a bb before so i know they are great but i dont wanna pay 60 dollar every month so i was hoping that i cld have the bb on the 50 plan.........do any of u know if this is possible?? thanks