Travel help: Getting to Günzburg Legoland from München airport

Hi! Strangely enough, I couldn't find any sound advice for my problem from Google, so I'll try here. Apologies if the question seems dumb.

I would like to know if there is a reasonable way to get from Munich Airport to the Legoland in Günzburg. I found some transfer sites that are willing to organize this for about 500 EUR, which seems like an astronomical amount of money. We're a family of 4 and will be travelling in April. Should we just get a train to Günzburg Bahnhof and find a bus to Legoland or is there some kind of app that locals use or something other that I'm missing? Thanks in advance!