If you have a SCSI card, there are lots of older scanners around for cheap. You could look for a Minolta Scan Multi, which handles medium format, or an Agfa Duoscan, which handles transparencies up to 8x10". The two images I posted recently in the standard gallery were from the Duoscan Solo, which is the least capable of them. The most desirable would be the Duoscan HiD, which has better resolution and higher Dmax. Duoscans of various types can usually be had for anywhere between $25 and $150, depending on model, condition, and accessories. If they have the glassless neg carriers, they are handy, but if not, you can sandwich the negs/slides between two pieces of glass using the standard glass transparency tray.
Do you have a digicam? If you do, you can also digitize negs and transparencies with a digicam, a tripod or copy stand, and a lightbox, and it works for any format that fits on your light box. Some of the older images on my website were digitized this way, like this cheesy travel shot: