Amazon offers Prime members the Linxup OBD GPS Vehicle Tracking Device, model no. LPVAS1, for $24.99 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.14.) That's the lowest total price we could find by $23. It allows you to monitor fleet driving activity and review driving routes.

Note: The tracking service costs $22.99 per month.