I've been reading this thread and I'm not going to comment on if I think any position is the correct one - everyone is entitled to their opinion and none is more right or wrong.
I'm a big fan of finding middle ground where everyone is not 100% happy and no one is 100% unhappy - everyone gets something.
My suggestion would be simply to make a prerequisite for the purchasing of PowerStore. If you own the five main extensions (eCart, SecurityAssist, DataAssist, Universal Email and Validation Toolkit) either by purchasing them separately or via a suite, then you can purchase PowerStore. Otherwise you can not buy it.This allows those that want to use it as a learning tool or a starting point to purchase it. It also prevents someone's client from finding it and buying it for $200.00. Essentially you take the price of Powerstore from $200.00 to Powerstore plus the cost of the other extensions.
My personal experience is that it's more work than it's worth to retrofit a custom shopping cart from a pre-built solution such as PowerStore. My clients have very specific needs that come with a project scope and design brief. I've also spent the time to understand the tools involved.
Would I sell PowerStore as is? Yes, but... I sell PowerStore 2 as part of a package that includes hosting, ssl certificate, minimal design changes and we deploy it. The customer pays and within 2-3 business days they have a functioning shopping cart system. Down and dirty, but cost effective to those that don't want to pay for a "custom built" shopping cart solution.