Asuckaphish
Rock Stacker
Thats a steal! I never honestly thought of this but really its not a bad way to go, especially if you can test the rig and have a look at it.
With a 500$ budget you could get a solid platform for around 200$, and then upgrade the crap out of it and have basically the same high quality performance. I wonder if you could even part out a crawler entirely to save money having avoided spending money on a stock rig you will take half the stuff off of anyway.
Totally agree that buying used can be a great way to get a good deal. If the new person has a friend in the hobby who can take a look at the rig and determine if it's a good deal then i'm all for it. I think the problem is a lot of times new people don't know what they don't know and can easily end up with someone elses abortion of a build.