Camcorders can cost between $50 and $50,000. "good quality camcorder that doesn't cost much" is too vague.

How often the camcorder is used and for how long has little to do with the quality of the video you require or the price to purchase it. If your budget is around $1,000 you have an OK selection of mid-to-high end consumer cams. Those with a firewire (IEEE1394) connection will limit you to the Canon ZR960 (standard def only) or HV40 (high definition) and Sony HDR-HC9.

High definition or not?
Firewire connection or not?
Details on the computer running Dartfish will be important.
Does the computer meet (better yet, exceed) the MINIMUM requirements posted at the Dartfish site (lower right, in "Product Documentation"). "Almost" does not cut it.

There are several versions of Dartfish - which one do you have?