The NEX-7 is the only NEX with Wireless TTL support. However the built-in flash cannot command (which is an oddity in the Alpha system). You\'ll probably want an FVL-20 as a commander flash and then some Metz or Sony flashes as slaves (avoid any other brands, especially Sigma, they don\'t play well).
The biggest caveat is which flashes to go with, the older flashes (the FVL-56 and FVL36, their Minolta twins the 5600HS(D) and 3600HS(D)) don\'t support multi-group flash on digital bodies. I\'d go for the FVL-43\'s for cheap slaves or a mix of them and at least one FVL-58.
Note Krosvacheg is correct if you don\'t need TTL capability. No point in selling off 4 working flashes to replace with off-brand flashes that are inferior to your Canon speedlights anyways. In that case I\'d sell one of your Canons to help fund some triggers and get a FVL-20 for on-camera fill.
