Here was my recent advice from the thread I think you were looking for:
I don't look at SMR as I think it can be inaccurate. The free sources I use for price info, in no particular order, are:
1) Ebay (search the card and then check the completed listings box on the left)
2)
www.pricerealized.com (free without a user name going back 18 months, free for 36 months if you create a log in)
3)
www.cardtarget.com (free, though doesn't have the most recent sales - a nice way to look at older Ebay data)
4) Google (search the card, grade if necessary, and add the word auction)
5) Search the appropriate BST section on Net54 (often not much use because people tend to delete prices when an item sells)
VCP does a nice job of providing a price history but isn't a free service.