Before you can buy bitcoin on their exchange you have to deposit fiat, and the fee for depositing funds with credit or debit cards is 7%. Ouch. Here is a table of their rates.
For the 1st transaction with a new card transfer an amount between 5 USD and 15 USD. The second purchase can be made in 4 days (100 USD Limit). The third payment can be made in 7 days (500 USD Limit). If your card account currency is other than USD, conversion will be completed at a rate of your bank.
For the first month your limit is $500. After 40 days the limit on card purchases is raised to $3,000.
Besides the credit card fees looks like they are making money on the bid/ask spread.