A best bet for Amazon Prime members is the Case Logic SLR Sling Case (pictured), model no. TBC-310, for $19.99 with free shipping. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.73.) That's $20 under our September mention and the lowest total price we could find by $16. It features hammock sides, zippered pockets, adjustable side straps, and more.
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. (Note that currently there's a waitlist for Amazon Mom.)