My dad has an HP DeskJet 990C. On his printer, with his drivers, I can select a paper size of "4x6 with tear-off tab," which is precisely what I have to print on (HP Premium photo paper).

Standard Printer Paper Dimensions. Most business printers can accept a broad range of paper sizes within their sheet-fed paper trays. This flexibility lets you use one printer to handle everything ...

"This driver does not support the banner and custom paper printing supported by the Mac OS 9 printer driver." users cannot print to custom papers sizes in Mac OS X using Epson or Canon printers.

Double the paper size again to A2 and the price of the printer roughly doubles too. A1 and A0 printers are generally aimed at enterprise as the cost of the printer and ink is considerable.