For the Brystons your best bet is
http://www.audiogon.com
As this a site of mainly classified postings by "audiophiles" selling used gear safest way to use it is to do an advanced search by zipcode so that you can find sellers in your area so you can actually go and audition the equipment first to make sure it is in good working order before purchase.
For used effects processors I'd check:
http://www.roguemusic.com/ http://www.vintageking.com http://www.soniccircus.com/
Best regards,
Steve Berson