The alternative would of course be to get an ECP to provide direct authorisation for your cards. ViaWeb (now Yahoo! Store) charges $100 per month or a basic shop, although I think they charge extra for direct authorisation. Intellnets ishop (coming very soon I believe) charge £60 for a basic shop, but they do offer full authorisation in that cost through an X25 line to the bank clearing houses (X25 is the same system major supermarket chains use) though they charge %5 per transaction for the use of this facility.
If anyone is stuck with a commerce solution then a good ECP is prob the easiest way to go. A word of warning though, its worth looking arround to see what you can get for your money.