folsom_lives
pretty_lil_dirt_boi
I loathe Reddit, but after I get a tax bill for discogs I may change my tune...Have you tried Reddit? You could probably shave a few bucks off given the no Discogs fee aspect of it all and the market for VMP and Indie there seems to be fairly strong.
To your original question, it's definitely a space and patience thing. I'd hypothetically say forever if space or collection size wasn't a limitation but to Kris' point, between the tax, effort, and honestly sheer satisfaction of clearing out stuff you're not gonna listen to it may be worth the trade in.
I even tried selling through the forum here but too many comments from the peanut gallery turned me off. Might be time to jump back in if only to say N&G discount.