Took that Sonic & The Secret Rings along with my old copies of Strider and Star Wars Shadows of the Empire into my local shop.
They offered me $15 in credit for them (pretty good since I paid $8 for the Sonic and the better carts), and here's what I got...

XBox - Splinter Cell (Need this to mod my XBox) $1
N64 - Star Wars Rogue Squadron
$5 (Three for $10 deal) $3.33
N64 - Body Harvest
$5 (Three for $10 deal) $3.33
PS3 - Infamous
$5 (Three for $10 deal) $3.34
And most importantly:
NES - Jetsons: Cogswell Caper
$30Admittedly, the label's in kind of rough shape on the top edge, but $30 for a game that goes for at least $70 online... Not gonna pass up.
It wasn't a slip-up, mind you, the guy who runs the store knew what it was worth, but he cut me a deal because the label being a little rough and because I'm in there every week. Loyalty pays off.