Selling a cello in Poland

I'm in Germany and want to sell a cello as a private person. I've found an interested University in Poland that wants to buy my cello. Now, they say that for burocratic reasons, I'll have to sell my cello to a polish music shop, and they will buy it from them. All is well so far, but the shop now sent me a proposal for the sales contract. In this contract it is stated that the sale took place In poland, and that Polish law shall be applicable to this sale. I'm confused here as the sale in fact took place in Germany, where I live, and I don't know Polish law or speak Polish, so I can't check what I'm getting into. I feel that it should state that the sale took place in Germany, and that German law should apply. Am I being unreasonable? Are there any taxes or obligations I would have if I stated the sale took place in poland and Polish laws should apply?

I think the music shop wants to abide by the law (or make it easier for you) by stating the cello was sold on Poland territory. I think it shouldn't matter for you - payment could have been done on the Internet and then the borders don't matter. If you're still worried, you may try to word it differently (eg. that the sale was "executed" in Germany, but payment was made in Poland). In general, I don't think it's something to worry about.

I don't understand what's so special about a cello, how is it different than another musical instrument like a guitar or a piano. It sounds like some old and no longer applicable piece of law.

Like good violins, the cost difference between the best and an ordinary one is huge, and there have been many issues over the years/centuries in Europe with fake ones that purport to have been made by famous craftspeople. A few countries have specific rules about their sale and about their export. The best ones are also considered part of a country's cultural heritage.