Check out Blueseventy Core Shorts @ Blueseventy.com
Lava shorts by Xterra @ Xterrawetsuits.com
The pull buoy is a valuable tool to keep legs afloat as you work on your stroke & build upper body strength. It can also give tired achy legs a break after a long day on the road. One of the main drawbacks to the pull buoy is that it really does not mimic the same buoyancy & rotation characteristics as a wetsuit. At around $99 many of the wetsuit companies have introduced core shorts or, as Coach Rob calls them, "cheater shorts." This tool gives the lift of a wetsuit & also allows the hips to rotate properly.
Cheaters are ideal for drill sets, recovery days and early season, long pull sets. Check 'em out.
While you are at it, check out TYR hydrofoil Ankle Float
A great swim torture device designed to add resistance, develop good core strength, the float requires more strength than traditional pull buoys. Retail is about $20.