No, you give them your account and routing number, and they pre-print it. It has to be printed with a special MICR ink and with a special font. You can buy a cartridge of such ink for your printer and print it yourself on a bunch of stock check paper, but it won't be any cheaper.
More information about the MICR line on a check:
The bottom line on all checks printed and used in North America (and many other countries worldwide) is printed using a special font called MICR (short for Magnetic Ink Character Recognition). MICR is usually pronounced My-ker. The bottom line on a check must always be printed in the MICR typeface using a special magnetic ink.
The MICR line on a check allows the check information to be automatically read by inexpensive machines. This is the only way that huge numbers of checks can be processed each day.
MICR line printing needs to be accurate to better than 1 part in 1,000! Your magnetic toner must stay on the paper under adverse conditions and have a specific signal strength.
You can look at prices at Walmart, Costco or Vistaprint, they're all pretty cheap.