In a press release issued Monday, Apple (AAPL) lists “most Best Buy stores” among the places — along with Apple.com, Apple retail stores and selected authorized resellers and campus stores — where customers can buy iPads on April 3.

But would-be buyers who show up at the 675 Best Buy (BBY) stores privileged to carry the tablet computer this Saturday better plan to get there early.

According to an internal memo leaked over the weekend to TUAW.com, only Best Buy stores with “Apple Shop” displays will carry the devices. And those stores will receive only five units of each iPad  model (16GB, 32GB and 64GB) — or a total of 15 iPads per store — for Saturday.

Moreover, not all those iPads will be available for sale. Four must be marked “Not for Resale” and set aside as demo units. These iPads, the memo warns, “cannot be sold under any circumstances.”

And the fate of the 11 that remain is even in doubt.

Fifteen iPads are promised for delivery by April 11, but the memo adds that “inventory will be extremely limited … In the event Apple cannot make inventory for April 11, stores will need to hold inventory from the April 3 shipments for the April 11 ad” (a reference to a promotional campaign scheduled for the following week).

“We can’t wait for users to get their hands and fingers on [the iPad] this weekend,” says Steve Jobs in a statement prepared for the release.

Getting their fingers on it may be all most walk-in customers get to do.

Below: The key bullet points in the Best Buy memo.

[Follow Philip Elmer-DeWitt on Twitter @philiped]