I would also keep it as it would be great as a JUST IN CASE tank
Hm for"- over the side heater
- aqua clear mini filter system (I might even consider buying filters to put in with it)
- thermometer
- wood colour stand with shelves and doors
- some possible decorations
- maybe a pump and air bubbler"
I wouldn't really pay much. A 10g tank is $7.99 new, the aquaclear is <$25, stand I can't really say, need pics of that. Decor nothing almost used, pump $4.99 new and bubbler same if not less.
I'd pay $40 at the very most.