I think it boils down to finding the right buyer, which may be tough for such a specialized item. I sold my Monoprice 133" Grey Screen for $500 on Craigslist, which was about what I paid for it new, less shipping. It took about 3wks to sell. After talking to the guy, the key for him was the size and after seeing it mounted with picture, the quality. For the price, he figured what the heck. Key thing was, it was exactly what HE wanted.
The screen you are selling is more high-end than mine, however if one is going to pay $1K or more for a screen, then new ones start to look alot more apealing. Its a tough deal, because a newbie probably wont spend more than $3-500 for a screen unless they can see it in person and even then it may seem like alot of money for a screen. Someone experienced probably figures, they can get a brand new one for a bit more than what your screen is truly worth. Hard to find just that right person that is in the middle, especially if that person is local. Casting a wider net might get you more intrest, but shipping will likely scare them off. Large 4 piece screens typically ship by freight and can cost more than $130 to ship (at least my monoprice screen did)...thus making the screen seem more expensive.
Bottom line...establish a price you can live with and keep it advertised until it sells. The right person will come along.
Theatre: Epson 6010, Carada BW CS 142", Yamaha RX-A3020, Amp: Emotiva XPA-5, Fr/Rr/Ctr: SVS Ultras, Pres: Def Tech: SM450/SM350, Rr Srd: Def Tech: SR-8040BP, Subs: Dual PB2000, Dual PB1000
BDR: Epson 3010, Vis Apex 135", Denon 4520, Fr/Rr/Ctr/Pres/WideInfinity RS-10/RS-5/CC3/RS-3(4), Subs: Dual PB2000