Covershield via eBay offers the OxGord OBD II Diagnostic Car Scanner for $13.45 with free shipping (Amazon charges the same price.) That's the lowest price we could find by $3, although we saw it for $2 less in February. It works on 1996 and later OBD II compliant vehicles and features a back-lit LCD display.

Update: The price at Amazon has dropped to $12.95 with free shipping for Prime members.