Tin Signs

Desperate Sign Co: http://www.desperate.com/

FiftiesFun: http://www.fiftiesfun.com/

Comic Books

Amazon: http://www.amazon.com

AtomicAvenue: http://www.atomicavenue.com

ComicBase: http://www.comicbase.com
ComicBookRealm: http://comicbookrealm.com/ (Free catalog w/Ebay links too)

ComicConnect: http://www.comicconnect.com

ComicLink: http://www.comiclink.com

Hakes: http://www.hakes.com

PacificComicExchange: http://www.pcei.com

Source Comics: http://www.sourcecandg.com/ (Hans Spitzer)

WikiPedia Comic Book Price Guide Entry: http://en.wikipedia.org/wiki/Comic_book_price_guide

Well Known Auction Houses

Bidstart: http://www.bidstart.com

Christies: http://www.christies.com

Ebay: http://www.ebay.com
Early American History Auctions: http://www.earlyamerican.com/

Heritage Auctions: http://www.ha.com

Numismatic

American Numismatic Association: http://www.money.org

Philatelic

Frajola PhilaMercury: http://www.philamercury.com/browse.php

Siegel: http://www.siegelauctions.com/