Pricing a frame for re-sale?

Before I post a frame for sale on the classified section, I am trying to research the best list price.

Frame is a Trek Equinox 7, size 52. Doesnt fit the owner properly and she (my girlfriend) is looking to sell it. I will look for other trek frames for sale to use a comps, but still intersted in peoples opinion.

I believe the full bike retailed at $1500 two years ago when purchased.

the frame is in great condition. What could we realistically expect to sell this for? $500?

Thx for feedback.