Restocking fees and non-refundable deposits are the same thing. Many products are now sold in this way, and sometimes we don't find out that there's a non-refundable deposit until we go to return the unsatisfactory product.
With the relaxation of regulation and fraud prosecution, such deceptive selling practices, long abandoned, have made a comeback. The marked price of goods is no longer their real price; instead, there are many hidden charges. The hidden charges may appear beforehand, like shipping charges, or afterwards, like the non-refundable deposit, which bites when the product turns out to be unsatisfactory. The price of a product becomes the stated price, plus whatever the hidden charges are, and buyer beware.
Do not, also, underestimate the costs of time in a purchase. An online purchase from a distant seller may in fact have a lower price, even after shipping charges are included, but by the time it has been shipped and received, and possibly exchanged once or twice, it can easily be a month, whereas the same transaction made at a local store, provided the goods are available, can usually be completed in two or three days.