Chief makes mounts with variable down extensions, some even adjustable. Pair it up with the RPA-U ceiling mount and you should not have to buy another mount for awhile. As for which PJ offers the offset, I know the JVC should Epson 1080UB, and maybe even the Panny 3000( worth it to ask here).
For 720p Epson 720, Mitsubishi HC5500(full 1080), Panny 200U are all under 2k and should work also. Check out projectorpeople and read the full specs and go from there.