Local transportation tickets at Budapest main train station.

Which train station? There are three main train stations in Budapest. Nyugati, Deli, and Keleti.

The Keleti station.

Yes, you can use the machines at the train stations. I am not 100% sure, but those are for trains.
Metro and bus tickets, I have always purchased by the window attendant at the metro stations.
Hope this helps.

Each of the two main train stations (Keleti & Nyugati) has a metro stop one flight down. At Keleti the steps are located between the front wall and the front of the trains (inside tracks). Besides the windows there are easy to use vending machines too, but i always heve used cash in the vending machines. If I pass a vending machine in the next couple of days i will try my American credit card and see if it works. I once tried to use my American CC for train tickets and the train ticket machine requested a PIN. Having nothing to loose I put in 4 random numbers and got my ticket. So who knows?

I was in Nyugati station today and noticed that there was an ATM. I assume there will be one in Keleti as well. But, if at Keleti you were to go down the stairs I described in the previous post, at the bottom, on the right is a new information center and they can help you with everything.

Thank you all for your help. Good to know there is an ATM machine. I can rest easy now.

I misread, but I imagine there probably is one at the other station, too. If not at least there is the information center!

I would bet money on there being one there. I may still get over there this week. Taxis take credit cards if that makes you feel better. Never hail a taxi, always phone for one. My favorite company is City Taxi.