Why would you want to buy used styli? Headshell/carts, sure, buy stay clear of second hand needles imo...you have no idea how mistreated they might have been, how crap the guys vinyl collection was etc.

Other than that, don't know of a site specific for this, sorry...eBay is probably the best bet
Pete Gordon - Deep and Low

Slower tempo but still with balls, deephouse, slow-mo, futurehouse, nudeep, indie, nudisco, hints of progressive, whatever the fuck you want to call it, just good shit! Get on it