Adex Electronics: http://www.adexelec.com/--cheapest PC/104 to ISA adaptors I have found; AR-B1052 and AR-B1053.
Arvoo: http://www.arvoo.com/--Picasso line of PC/104 mono and color frame grabbers, claimed to have Linux support.
Sensoray: http://www.sensoray.com/--their model 311 frame grabber is stated to have Linux support.
Ajeco: http://www.ajeco.com/--commercial PC/104 frame grabbers. Web site is light but has contact information. The ANDI-FG works with Linux.
Digi-Key: http://www.digikey.com/--good source for connectors and other essentials.
Zerospin: http://www.zerospin.com/--Cliff Leong, writer of the Videum Linux HOWTO and wearable computing enthusiast.
Bill Dirks: http://www.thedirks.org/winnov/--writer of Linux drivers for several Winnov frame grabbers. The Video for Linux 2 page is also on this site at http://www.thedirks.org/v4l2/.
Hardware Book: http://www.hardwarebook.net/--diagrams and signal names and descriptions of ISA and PC/104 signals referred to in this document.
Quality Kits: http://www.qkits.com/--sells a low power, +5V supply B&W sugarcube camera in a DIP package.
ICUC Video Connections: http://www.icuc.bc.ca/--a distributor for Winnov.