I don't know if this applies to their rolls of plastic T-molding, but even if it's a high minimum order it says the prices are per roll. $50ish for 100' to 250' of T-molding would be an incredible deal.
The T-molding I purchased from them was sold in 12' lengths (it's solid metal) and I ordered four of them. 48' total, so no minimum was enforced there. I asked about it and she said it would be fine to order only one of them.
The site really is attrocious.