This posting on Audiogon for an ARC REF 5 for only $4250 appears to be a great opportunity to be ripped off. The seller is in Spain and has zero feedback. The REF 5 is listed as being in 9/10 condition but there are no pictures.
http://app.audiogon.com/listings/tube-audio-research-ref-5-preamplifier-2013-10-09-preamplifiers-spain
http://app.audiogon.com/listings/tube-audio-research-ref-5-preamplifier-2013-10-09-preamplifiers-spain