i think the best cheap sailboat is the nirvana pro racing series. Its not rtr, but it's really easy to put in the electronics. its really great at sailing and it's got such a sleek hull. ANd it has good components like a corbon fiber mast and mylar sails. I just got one a few days ago it's amazing.

Links for the stuff you'll need:

boat:
http://www2.towerhobbies.com/cgi-bin...?&I=LXFGA1&P=0

Radio 1 (if you want a sail servo that needs modifications to fit in the mount) <----i highly recommend this, it isn't hard to modify the servo mount for the sail servo
http://www2.towerhobbies.com/cgi-bin...I=LXGRM9**&P=0

Radio 2 (if you dont want to modify anything, but suffer a great loss of sheeting power)
| Radio: http://www2.towerhobbies.com/cgi-bin...I=LXGRM7**&P=0
| Sail servo: http://www2.towerhobbies.com/cgi-bin...?&I=LXDTB3&P=0

$2 Radio Ratcehet conversion (so then the left stick ((the sail control)) doesnt center itself, but ratchets)
|the ratchet arm: http://www2.towerhobbies.com/cgi-bin...?&I=LXH435&P=M
|the screw: http://www2.towerhobbies.com/cgi-bin...?&I=LXH436&P=M

whew, that took a long time to find those lnis, well... enjoy!