If I have only a few 6x4 prints to do, I do them at home, if lots, I take them to whichever high street place is doing the best deal at the time. For A5 or larger, I do the printing at home. I also take a little DyeSub printer on holiday so I can send back my own photos as postcards. IIRC, they work out at about 17p each - not cheap for a 6x4 print but cheap for a postcard. (The little printer is a Canon Selphy CP710 and the ink/paper packs came from 7day)