Here are some condo's where my son's team stayed the last two years. Actually there were 3 or 4 teams who stayed there. Great place and about a mile from the fields. They are usually booked well ahead of time, but maybe you can get lucky. It's around $145 a night.
http://www.shorewalk.com/Us poor folks stayed at the Days Inn two years ago for about a half that. Not the best, but we only slept there so it wasn't that bad. It was centrally located and not that far from Pirate City (Pirates spring training facility).
There are some great places right on the beach $$, but 20-30 minutes away from IMG (depending on whether the draw bridge is up or not
.)
There are also a bunch of hotels by the Bradenton Airport, but they are a long way away from the fields. The hotels right outside of Sarasota are actually closer. We stayed at a Howard Johnson's in Sarasota last year. It was pretty close to the fields, but about the best I can say is the rooms were clean.
Good luck and have fun.