Vista Print The folks who bring you those free business cards — also free postcards — 100. A little smaller than standard — 5.47″ x 4.21″ — upload image for front and back. Probably higher S/H, but still, free 100 cards….
USPS Much cheaper than Kodak, can get with return address imprint & postage.
http://www.cardstore.com/asp/usps/index.cfm?page=photocard
1-9 $1.09 each 4�x6
Cafe Press (now has “create & buy,” skipping making one’s own store)
http://www.cafepress.com/cp/customize/product.aspx?clear=true&no=77
Custom Greeting Cards (Pkg of 6) $10.99 5″ x 7″
12pt single-side coated glossy paper. image inside & outCustom Postcards (Pkg of 8) $5.99 6″ x 4″
12 pt paper
Kodak
http://www.kodakgallery.com/CardStoreLanding.jsp?
1 – 9 $2.99 each
Apparently the folks at http://www.psprint.com/index.asp have good pricing: 150 for $30-some (the smallest order) — 2005-11-14
http://www.zazzle.com — no postcards (yet)