Keep in mind that (if they are real) these are bullion coins and are worth the value of the precious metal plus a small premium. I don't know offhand the actual gold weight (AWG) of the Mexico coin and you didn't say what weight of Maple Leaf. If you know the AWG you can easily estimate value at a given gold spot price.
For example, gold is at $884 per ounce (today's price), so the 1/20-oz panda is worth ($884/20) = $44.20. If it's real and you can get it for $40 it's a good deal. If they want $100 then it's a bad deal, even if it is real!