Official comment
You can definitely do that, with the caveat that you have a relatively small number of products. Our current solution would get unwieldy with a large product catalog.
I'd create custom object for 'products' and add a record for each. I'd include product name and inventory amount.
Then, I'd use the Dynamic CMS to make my sales pages and create templates or dynamic blocks based on Products, depending on how you want things to look.
You can make as many templates as you like if you want them to all be different, or you can make one and use merge fields from the product object to create those sales page elements.
Or you could have a bunch of static pages and put a dynamic block containing your order form.
Either way you go, you'd create a rule or an automation such that when the form is successfully completed, the product record has 1 subtracted from the inventory field.
Then, you'd create conditions to only show the order form if the inventory is greater than 1. If not, you'd show something else.. like a 'sign up to be notified when this product is back in stock'.
This should work great, and you can notify your team when stock gets low, etc. The reason it would get unwieldy at scale is that you'll have to set up an automation or rule for each product you have, which is fine for 10 or 20.. not fine for 100 or 1000.
Hope that helps!