Best Buy offers Dragon Ball Z: Season 1 on Blu-ray for $9.99. (Amazon offers it for the same price with free shipping for Prime members.) Opt for in-store pickup to avoid the $3.99 shipping charge. That's the lowest price we could find by $8. It includes all season one episodes across four discs.
Update: The price has increased at Best Buy; however, Amazon still offers it for $9.99 with free shipping for Prime members.