Are these guns new or used? It all depends. Especially on the condition of the gun if used.
If the gun was New In box for the Rossi then it goes for $225. There are cases of these being bought and then put away and forgotten,then pulled back out and in great condition.
Here's the rest.
Excellent:$175.00
Very Good:$150.00
Good:$125.00
Fair:$100
Rossi 68s come with 2 or 3 inch barrels only. If that is a 4 inch barrel then it is likely that that is a Rossi 851 or a 951. 851s are in production. 951s are not in production.
For the Taurus 82 it depends if it is stainelss or blued.
Blued 82, NIB:$295; Excellent:$250: Very Good:$200; Good:$125
Stainless 82, NIB:$315; Excellent:$265; Very Good:$185; Good:$125
I own a new Taurus 82. I find it to be an accurate,dependable, and seviceable revolver.
If you need a source for Rossi 68s there is this.
http://www.taurusarmed.net/forums/rossi-revolvers/
For Taurus 82s there is this.
www.taurusarmed.net/forums/taurus-revolvers
Not sure what the condition of your guns is. You'll have to tell us.