Amazon offers its Prime members the Philips AVENT BPA-Free Classic Polypropylene 9-oz. Baby Bottle 3-Pack
with free shipping
. (Non-members can spend over $25 for free shipping; otherwise, shipping adds $5.34.) Outside of the price below, it's the lowest total price we could find by $8. These dishwasher- and microwave-safe bottles purport to reduce fussiness and colic (which are conditions that your human babies suffer from).
A close price is Drugstore.com's $11.59 (check the "Online Coupon" box to get this price) plus $5.99 for shipping.
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.