Mixing analog speakers with new wireless ones?

feetofflames

I have two TSi400 tower speakers hooked up to a receiver and am looking to add more speakers which will likely include center, rear sides, possibly another 1-2 in a different room of the house. However, our house doesn't allow for convenient hidden wiring (no access above the living room) so I'm considering wireless speakers just to make it easier. How would I be able to use both? I have the TV and my PC hooked up to the receiver and would like to be able to use the whole system to play from either source. I saw that there are analog -> wireless amplifiers but they are really pricey and ideally I'd like to still use the receiver system and love my tower speakers so don't want to replace them. Any suggestions/help??