Have a look around for something like a Dell Optiplex GX260 SFF or any other small form factor machines. The Dells tend to go for between £40-60 and have the full parallel port capabilities. I normally use them as they're quite neat compact units. One of mine sits in the cupboard on the boxford lathe, another will be going inside the 260VMC.

Just make sure they come with the power brick as well ;)