MikeyMike,
I have an Canon i860 that I HIGHLY recommend, as long as you don't need more than letter sized (or legal, or 8.5" wide) prints.
All my friends helped my wife pick it out for my birthday and so far, I can say that it's phenomenal. The ink cartridges are very inexpensive as well, as low as $4 each if you shop around, or $12 for original Canon cartridges ($50 to replace all five).
I've had mine for 23 days now, printed out full color images on everything from photo paper to legal sized paper at the rate of roughly 2-3 prints per day and so far (where is wood in cyberspace to knock on?) it's been a great printer.
Me personally? I will probably stick with OEM cartridges because I don't want to take the chance on screwing up a great printer, even if it was a relatively low-cost item.
If your customer's printer is USB, you MIGHT consider checking to make sure that the different USB devices aren't conflicting. It's not supposed to happen, but every time my wife goes to scan something, her wireless USB network card dies.