I've been experimenting with enlarging some of my sketchcard/ACEO portraits to postcard size and have just listed the first two
on Ebay (Emma Watson & Russell Crowe), starting at 99p. I've also put them on sale at my eCRATER store at the regular price of £1.50 if you can't be bothered to wait 10 days for a potential saving of 51p - see
UK £,
US $, or
AUD $ . Not all my sketchcards will work at a larger size like this but I'll probably try some more.