most people wouldnt trade to you directly for CC since it can be easily reversed, but you may want to try and exchange; i think coinbase offers instant purchases if you buy with a credit card iirc.
Coinbase the fee's are higher for CC. I can't remember limits on it. They will limit it based on account, more activity and older more you can buy with CC.
With CC you risk chargebacks and stolen CC's. So this causes higher fees. I suggest finding a good exchange and set up a bank account for it. Most likely you can set up one with a small min amount to keep in it. Then use that account just for buying/selling BTC.
i think it was something along the lines of 1-3% fee for a credit card purchase, but im probably wrong on that, and i dont care enough to look it up. i only said coinbase because i know for a fact that coinbase offers CC purchases. I dont know if Circle offers it as welll, but if they did i would assume they have less fees.
Coinbase's fees are high with accounts too, got charged 1% recently for a purchase!
Why do you want to buy bitcoin with a credit card? Do you think the price is going to jump and allow you to cash out and make a tidy profit? Maybe that will happen, but you have a better chance doing it in the stock market (where there's at least analysis and data to support buying decisions) than you do in bitcoin.
Don't get burned going long on credit and ending up getting shorted. Seriously, bulls make money, bears make money, but pigs get slaughtered.
they also charge 1% on btc -> fiat conversions. iirc they also charge a flat 0.30 USD fee on every purchase as well, its pretty ridiculous on the fees, theres almost no incentive to use coinbase over circle. circle is also international, whereas coinbase's services are only available in the US.