I just sold a circulated $20 birthday note. Total sale price: $25.99 eBay fee: $2.60 PayPal fee: $1.11 Shipping: $0.55 Envelope: $0.10 Net total: $21.64 TOTAL PROFIT: $1.64 Conclusion: not really worth it.
Yep, that sounds about right. When an item's face/spender value is close to its collectible value, eBay and PayPal fees eat proportionately more of your profit. If it had been a $1 note that sold for $4, you would've made about the same profit, and it would've been equally not worth it, even though it sold for "four times face value".
The Bay and its evil twin sister pay pal are getting rich of the honest hard working american, with all the fees and the buyers asking for discounts, your 20 profit just turned negative...LOL
I'm guessing there are a lot of "honest hard working Americans" who wouldn't be too sympathetic over "I can't make a profit selling $20 bills for $25.99".