There’s a one-time set up fee of $15 and an optional $10 monthly charge if you want Etsy Plus for extra customisation and other features, but other than that there isn’t a maintenance fee.
For items there’s the 20 cent listing fee (that requires renewal every 4 months), then if you sell something there’s a processing fee (3.0% of the order total plus $0.25), transaction fee (6.5% of item total), and if the sale was made through Etsy’s Offsite Ads then they take 15% of the order total (everyone is automatically signed up to this, but you can opt-out). You can also optionally do Etsy Ads which will incur more costs, and starts with a default minimum of $1 per day. I’ve USD for all the numbers.
This is Etsy’s page about their fees: