What the cost consists of
The spread — how far the offer price is from the market rate; the platform fee; the network fee for sending coins to your wallet; and sometimes a bank fee for the transfer itself.
Large exchanges
On Binance P2P and Bybit P2P the person who takes an offer usually pays no separate fee, while offer makers may pay one depending on the market. You need an account with full verification, and moving coins to your own wallet is a separate withdrawal with a network fee. Conditions change, so check them on the exchange's website.
Garant Exchange
The guarantor's fee is charged only on completed deals and is shown before the deal starts. Coins go straight to your own wallet, there is no exchange account to top up, and ordinary amounts need no identity check in most countries.
What really matters
The spread often weighs more than the fee: a fee-free offer with a worse price can cost more than an offer with a small fee and a better price. Always compare the final result.
How to compare yourself
Take the same amount, find the best offer with your bank on each platform, add the platform and network fees and compare how many USDT you get for the same money — or how much money for the same USDT.