The number that popped into my head before checking the linked listing was $1200 - assuming the bulb still had some life in it. I paid $2500 for a used RS-20 about a year ago, with 600 hours on the original bulb, and a new spare bulb. That could probably be had for $2000 or less now.
I bought locally, and not sure I'd do it any other way - to have the ability to make sure you're not getting a dud (misconvergence, lens adjustment motors, etc.).