What are the fees for a transaction?

Using LOBSTR does not add any additional fees for the end-user. The regular Stellar transaction fees still apply, however.

To prevent ledger spam and maintain the efficiency of the network, Stellar requires small transaction fees and minimum balances on accounts (standard operational state). 

When network activity is below capacity, you pay the network minimum, which is currently 100 stroops (0.00001 XLM) per operation.

This can result in what looks like an uneven balance in your account.

Read more on Stellar fees here: 

https://www.stellar.org/lumens

https://developers.stellar.org/docs/encyclopedia/fees-surge-pricing-fee-strategies 

LOBSTR does not charge any fees when depositing or withdrawing assets through the deposit/withdrawal interface. However, asset issuers (anchors) may set their own fees for deposit and withdrawal operations with their tokens.