I found this auction on eBay. There are Dickie Thon and Doug Corbett autographed cards in the auction along with 7 other non-RBI'ers
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2731353619&category=53
Not bad for 3 bucks!
I go for the RBI player search every once in awhile and pick up some $1-5 gems. Last purchase was the autographed Rob Wilfong Smokey the Bear Card:
(http://dee-nee.com/rbi/pics/robby2.jpg)
Don't remember the exact price, but wasn't more than a few bucks. Also got a Tom Brookens autograph...