I want to buy new speakers for 50,000 and see it used for 30,000, what should I do?

$50k buys you a lot of speaker new or used. Call Mike Powell @11stereo.com. His F&F lineup is very good and he always has high end used gear for sale. I have made several purchases from him and he is good people.

@OP - your post does not raise a concern that very nice speakers are too expensive. With very rare exceptions, consumer goods depreciate. Not nice speakers depreciate and very nice speakers depreciate. Actually, very nice speakers depreciate less.  Speakers have a long service life so their depreciation can be amortised over many years. Anyway, that has to be set against the pleasure of listening them, and what price does one put on that.

I don’t believe you are crazy. 
 

I have a good relationship with a local stereo shop - and I go there for all my purchases (new or used). They deliver, set-up and stand by the product. On demos I get the warranty and in some cases manufacturers (e.g., Wilson Audio) have certified used programs. 
 

Good luck!

I would buy the used speakers if and only if I could see/hear/touch them beforehand.

I've never considered the fact that I have a wife unfortunate or unlucky. Guess it all comes down to choices, eh?

If you’re spending that much, go inspect in person, listen, heck even tote your amp and cables. You can afford the flight, a first class hotel, steak dinner with a bottle of Lafite to celebrate purchase with what you’re saving! Unless you hate them, then you’re saving more.