Take the volume of your setup. Assuming, it's average, run off the mill equipment, start $10/gallon for ballpark pricing for a quick sale on a bare bones setup. Tank, stand, sump, etc... Add equipment maybe 30-50 percent what you paid. Then bump it up or down from there depending on your comfort with the price.
If you're patient and have high end equipment then bump the price higher.
Sent from my SM-N960U using Tapatalk