FWIW, in the LSX market, the HPTuners system works with credits, so you can buy multiple VINs (so to speak), and they're less than the initial cost that includes the hardware.
This does a couple of things: discounts for multiple cars and simpler ownership model (it's only one piece of hardware, one device to keep updated, use, etc.) It does introduce the potential for a single hardware buyer, using it on cars they don't own via credits, *but* I'd think most buyers would opt to actually own the device and have it in hand (for the difference of owning vs. just a credit).
I don't think having to return it to have it "reset" for use on another car is a really a big deal (I did that with another LSX tuning device, it was $75 including return shipping), but it depends on the cost. While there is _some_ overhead to receive it, run some diags, reflash it to "new", and repackage and ship, I would think that would be a reasonable fee of not more than 15-20% the original cost of the product.
Just my $0.02.