Cloudy Nights and The forum you’re on right now have an on-line marketplace. Generally, plan on getting around 50%-60% of its original value if you really want it to sell.
TL;DR: Upgraded quickly after getting my first rig and now have two fully functional rigs. Sell the first rig or have two rigs? I got bitten by the astrophotography bug pretty hard. After initially buying a Dwarf3 for my son in July, I bought my firs...
Relevant - discusses selling equipment after upgrade, similar situation to author's telescope sale.