Amazon offers its Prime members Sin City on Blu-ray Disc
with free shipping
. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $2.98.) That's the lowest total price we could find by $6. This 2-disc set includes the theatrical, recut, extended, and unrated versions.
Amazon Prime membership is $79 per year; however, Prime is free for college students for six months, and free for parents and caregivers for three months.
Update: Of note, Best Buy offers it for $6.99 with
free shipping free in-store pickup.