Buying tix prague->budapest (and muc->prg, bud->muc)

Hi, I'm looking to buy train tix for munich->prague->budapest->munich. It looks like the cheapest way to do this is to use www.bahn.com for the munich->prague and budapest->munich links... What's the best way to get the prague->budapest leg? Is there a local website with cheaper rates than raileurope.com? Or can we wait till arriving in Prague (we'll arrive on tuesday and try to get a night train on sat or sun night). Thanks,
Ram