regular vinyl & CD shops:
www.breakbeatscience.com (USA)
www.digalittledeeper.net (Germany)
www.dynamicrecords.at (Austria)
www.grooveattackrecordstore.com (Germany)
www.h-a-b.org (Germany)
www.otaku-records.de (Germany; ask via email!)
www.redeyerecords.co.uk (UK)
www.triplevision.nlm (NL)

special vinyl & CD shops:
www.discogs.com (database with "sell/buy" option!)
www.gemm.com (marketplace for rare items)
www.htfr.com (marketplace for rare items)
http://listings.ebay.de/aw/plistings/category7778
http://listings.ebay.de/aw/plistings/category7769
www.musicstack.com (marketplace for rare items)
www.nylvi.com (network-based label-stores)

vinyl & CD & digital shops:
www.breakbeat.co.uk/digital (UK)
www.chemical-records.co.uk (UK)
www.juno.co.uk (UK)
www.dancerecords.com (USA)

digital only shops/portals:
www.beatport.com
www.beatsdigital.com
www.digital-tunes.net
http://ithinkmusic.com
www.strictly-digital.com
www.trackitdown.net
www.tunetribe.com

some of many exclusive digital shops:
www.psidream.com/goldenoldies.html
www.trackdonalds.com

more: see www.dnb.neverseenbefore.com