If you are looking for a house then I would recommend Melborne area. My in-laws have friends that live there and have been looking at the prices there versus over here in the Tampa/Clearwater area and it is much more affordable.
However, if you are looking for a condo then I would recommend looking for something in the Sand Key, Indian Rocks, Maderia Beach area over here West of Tampa. There are lots of condos for sale that are on the intercoastal waterway and then you just walk across the road (literally less than two block walk) to go to the beach. We have friends that just bought a condo in Indian Rocks and they've been able to rent it out all winter to one couple. Our friends come down from Washington DC (like this weekend) to use it when it's not rented. It's going to be their retirement place in 20 years.
I would also consider if you are going to live here full time versus part time and renting out the rest of the time. Either way you'll want easy access to shopping and restaurants. Having access to an aiport near by would be good too! If you like little sleepy beach towns then Cedar Key (about 2 hours north of the Tampa Area, right under where Florida bends on the Gulf Side) would be a nice place to check out as well.
There are a lot of options on the West Coast of Florida - Ft. Myers area north is still developing. I think you need to take a trip down here and drive the coast.
Let me know when you're near Tampa/Orlando. We have a great group of girls that get together regularly and we'll be happy to show you around.