Well, actually it's pretty cheap.

I have a big, business type printer which is expensive for ink, so I purchased a cheap printer ($10, eBay of course), and the ink is $16 (eBay again) for 10 cartridges. Cheap as chips and SO convenient.

No PO needed either. You print out the slip, pop it straight into any red post box (assuming your closest isn't at the post office).