Finding ticket office for these two castles is not difficult. On every cca 20m, starting from parking, you have tables like the one on the picture giving directions. Be prepared to wait in line a few minutes. Lines are huge, but they move quickly. YOU CAN'T BUY TICKETS ANYWHERE ELSE! There are no tickets on the castle! Admittance for children under 18 is free of charge and they receive a free ticket Buying a "Royal Ticket" you get to visit both castles at the same day. First you visit Hohenschwangau and about 2h later you visit Neuschwanstein
Both castles provide their official souvenire shops, but as everywhere elso those are crowded and a little bit more expencive than off-site shops. My husband and I grew very fond of this Galeria for it's beauty and extremly good offer. They have everything: from castle models, bells and spoons with castle pics etc. to copies of Medieval swords, armors and cuckoocloks.
What to pay: You have to have in mind that you are in Germany and do not expect to bargain in shops. The prices are not cheap! For example, this middle size castle modell that you can see on the next picture, we have payed 15EUR