I played tennis Monday afternoon and noticed our tennis balls were just about through their useful life. After dinner, I started wondering how to replace them, living in my Upper West Side apartment, closer to the tennis courts than anyplace that would sell balls (the courts don’t, although they should).

Offhand, I couldn’t think of anyplace local to run in. Modell’s closed down, taking both local sporting goods stores out of our neighborhood. There’s a Target up here, but it’s way over on Columbus Avenue, and I don’t go over there much. We have some bodegas and 99-cent stores, but I’m not familiar with most of them, and didn’t want to wander around asking who has a sleeve of Pro Penns.

In an attempt to solve my problem immediately, I went, as we have been conditioned, to Amazon. Surely I could get some tennis balls shipped to the apartment before our next court time, on Thursday. (Disclosure: we are Amazon shareholders and Prime members.)

Turns out, yes, I could. But not in any useful way. Because Amazon’s model is cost-effective shipping, there’s no reasonable size worth buying; the site pushes you toward bulk: sacks of 18 balls, packs of 12 sleeves. Not what I’m after.

In addition, because Amazon is a marketplace focused on generating shipments with margin, the prices were awful. A can of tennis balls is $2.99 at retail, give or take. Not on amazon.com: they’re as much as $12, as I write this, for one sleeve of three balls. Even in bulk sizes, the prices don’t budge: I found $27.50 for four sleeves, for example ($6.88 per sleeve), and $59 for twelve ($4.92 per). Sure, you can get tennis balls tomorrow, but only if you’re compelled to leverage the free shipping and ignore the exorbitant prices.

Amazon’s current business model takes 34 cents on the dollar from its vendors. To sell me a four-pack of tennis balls, a reseller on amazon.com feels the need to charge $27.50 (at the time of this writing). After the reported 34% Amazon take, the vendor’s recognized revenue is around $18—still not three bucks a can, but at least not egregious. But Amazon isn’t concerned that the product is overpriced, it has that Prime lock-in. The site thus converts an ignorant shopper, traps a hurried one, or turns off one who’s paying attention. That last one, tonight, was me.

After a detour to the Dick’s Sporting Goods website, where tennis ball prices were fair ($18 for six cans) but free-shipping hurdles were high, I wound up on target.com. They sold me a four-pack of cans for $11.19. And because I have a similar relationship with Target as I do with Amazon, I threw in a few household staples and got free shipping, albeit a day or two slower than amazon.com.

And it turns out that Target on Columbus has individual tennis ball sleeves in stock. Maybe I’ll walk the dog over there and pick some up for Thursday.