Yes it can be expensive to do.. You may want to look at Printers that use a dye sublimation method. (wax based) these are water and finger resistant, but are as far as I know only up to A4 size there are a number of cheap postcard size ones.. But the quality is very good..

When storing in archival covers you need to let the inks dry for a few days.. before placing them in the covers.. Or speed up the process by drying  them..

Danny O'Byrne  http://www.digitalartzone.co.uk/

"All the technique in the world doesn't compensate for the inability to notice" Eliott Erwitt