I just installed Ubercart yesterday with no problems. I am selling craft one of a kind items. 99% of them are one time only sales, I create with a new SKU and set the stock quantity to 1..However the system allows me to buy as many as I want and I can find no easy solution to this.
I think what I would want is that the product stays visible but clearly marked as not available, and the the checkout button be disabled

