Flight: Budapest to Prague

Yes.

I use this site all the time to find flights. Enter in your city, no return, whole month and look at all the places it goes. I use it to plan all my trips...
http://www.skyscanner.net/

Smartwings makes the run for about 35 Euro each way, but it only seems to fly once a week, very early Friday mornings. Check out www.smartwings.net. Another option might be the train....one leaving around 7:15 and arriving around 2:30 pm via Vienna. Check www.bahn.de (click on "internat. guests) and http://www.vlak.cz/JRCis.asp?tt=c&cl=E5. You could probably purchase the train tickets thru raileurope, but I think a phone call to the German train company, (the bahn.de website) will get them more cheaply.