On the stickers, the quantity would definitely influence the price. If IWM stock levels meant that 500 stickers per mech type lasted them a couple of years then you'd be looking at possibly $0.20-$0.25 per sticker, but if they could go through 20,000 of a single type of sticker then you'd be looking at possibly $0.02-$0.03 for the same type of sticker.
The cheapest solution would probably be wait until they run out of the current backs, and then make sure the current design has a spot to include a QR code or a shortened web address that points to that mech's page on IWM that would be included when they print the variant info onto the card. At that point I think your biggest issues are that you'll need to keep the addresses the same for the cards to work, and how much time and cost it adds to printing the link/code onto the card.