Your winning bid is the starting point. Here's everything else that goes on your invoice, so there are no surprises.
The hammer price is your winning bid. The buyer's premium is added on top of it for every item you win. It goes to the seller and helps cover the cost of running the auction.
For items sold per unit, like a pallet of tiles, the item fee is charged once per item/lot, not once per unit.
It's separate from the buyer's premium. On your invoice, it shows in the fee breakdown as the Platform Item Fee.
Special fees can apply to one item or your whole invoice. They're listed in the auction terms, so you'll know before you bid.
Set your limit from your total
So if $237.50 before tax is your limit, set your max bid at $200. You'll see your estimated total, including the buyer's premium and item fee, before you bid. For how tax is added, see Sales tax and tax exemptions.