You're not getting 2 used sails for $500. You might get some dacron that's cut into a triangle for that, but not usable sails.
Are you doing any OD racing?
Does the rig have spreaders? Does the mast have any hardware on it? Spin pole, ring, ? Any clutches or cleats? Need to know if it has a rudder. A foam replacement will be close to $1k by itself. The shrouds will be about $100 each having a rigger make them and you installing them.
You don't provide enough information. That being said, the trailer is at least worth $400-500 by itself. And the topsides look great.
Merit 25 # 764 "Audrey"