http://www.artekmedia.com  This company sells high quality scans of manuals on CDROM

Consolidated Surplus, The Library of Manuals http://www.usimperio.com  I have purchased manuals from them via their ebay auctions and have been very pleased.

Manuals Plus http://www.manualsplus.com I have been amazed that they actually had some manuals for some very ancient test equipment. The best way to use them is to go to their web site and submit a list of equipment you want manuals for. Be sure to provide the serial number of the equipment since they may have the exact manual for a particular serial number series. They will respond by the next day with what they have and the price. I have bought a number of manuals from them and I have not had a case where they did not have the manual. Their prices are on the high side but their service is great. I highly recommend them.

W7FG Vintage Manuals http://www.w7fg.com This company located in Oklahoma is an excellent source for high quality photocopies of manuals for test equipment and consumer electronics. I have purchased a number of manuals from them and the quality is indistinguishable from an original. If the manuals did not come with comb binding and with their logo cover you would think the manual was an original. You can see a list of their manuals on their web site. They keep the site up to date but call if you do not see what you want as they are always obtaining new manuals. Since they only sell copies, they are never out of stock. If you see it on the web site, they have it.

Ridge Equipment Company http://www.ridgeequipment.com  This company sells both equipment and manuals.  I have bought much from them and have been very pleased.

Fair Radio Sales http://www.fairradio.com/   This is an excellent company and sells a lot of vintage hardware but also has an extensive collection of manuals for militarized equipment.  These are sold as photocopies at a reasonable price.