The only Falcon worth any serious money is the first issue Star Wars (aka A New Hope) one that was lighted. The cutaway and Return of the Jedi ones go for about what they originally did. The AMT/Ertl reissue ROTJ Falcon may go for less than the MPC original.
The Y-Wing fighter is the only one of the small snap kits that was hard to find and worth a bit more than its original price. X-Wing, TIE, B-Wing, A-Wing all made reappearances. Prices took a plummet once the Fine Molds X-Wing and TIE came out.
Snow Speeder still draws some money as do the R2-D2 and C3PO kits. The AT-AT is another kit that holds its value.