They don't get too high of a premium - if they have the special mint wrapping (orange logos and description) they are generally worth $15-$20 per roll of 40. If they come in normal bank rolls, the value is around $13 to $15 each. That said, you will find sellers who have sold 10 rolls ($100 face value) for $105 on eBay, meaning they lost money since eBay charges around 12% or so for its commission.

I used to find them at coin shows for around $11 or $12 apiece, but I no longer pay a premium now that the quarter press machines at Disney parks have been retired (I bought them to crush them).