This website uses xDai instead of Ether.
Ether transactions charge a "gas" price that is determined by "miners" who create the Ether coins. Websites using Ether can charge more than $100 for each NFT transaction.
The xDai coin is always worth approximately one U.S. Dollar, and the gas price is always the absolute minimum.
Each xDai transfer only costs $0.000021, so you can perform 1,000 xDai transfers for about 2 cents. To perform 1,000 Ether transfers would currently cost more than $10,000.
To convert USD to xDai: All major crypto exchanges can convert USD to Dai.
Use the xDai Bridge to convert Dai to xDai,
and perform the Metamask Setup Instructions to view your xDai in Metamask.