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

As Deep_333 said, the type of people that buy $50,000 speakers are not going to flog them. Their musical tastes likely run toward classical or jazz, neither of which are terribly hard on speakers unless deliberately pushed to the point of clipping. I’ve purchased used speakers since the early 2000s, and never had any issues. Ditto for speaker cables, interconnects and power cords, which I always buy used because they’re much less expensive AND already broken in. (I like MITs, which take 300+ hours to break in).

What’s my point? Instead of buying a new pair of $50,000 speakers, look for a used pair of $75,000 speakers (the ones you REALLY want) for $50,000. You may also be able to find a dealer that has some taken some back as a trade-in towards a higher model that will throw in a full factory warranty to sweeten the deal. 

Listen to them before you do anything else.....make sure the speaker works as intended

The OP’s B&W vs Sonus faber are very different sounding speakers.

Although I demoed several B&W 800s speakers, didn’t resonate with me and seemed bright.  Sonus faber is much more musical which translates to engaging.  Although we all have our personal preferences in speaker sonics, hard to imagine the OP not liking the Sonus faber

Bump, how did I miss this thread? My dilemma with the used +$50k speakers is how they'll sound in my room, with my components? My current speakers do nicely wity my $25k Mac front end, but what if those new speakers actually need the CH precision, Solution, Chord or gasp MSB components with $7-10k acc's to really get there?

I saved $25k on the speakers, but now have to shell out another $50-75k in used components and treatments. 

Every B&M dealer I've worked with has extended the offer to let me bring my gear in to hear and a couple dealers have even let me home demo speakers if they have demos on the floor. 

Once I start whittling away at the dealers price I'm trading their service in for a better bottom line and I don't have the experience they do with their products.

  Sometimes I think, if I could hire my dealer to set up my current system he could probably make it sound better than anything I bought at any price and set up myself.

There are a lot of really great speakers out there that are almost new for a significant discount. Dealer demos (ask them not to put “demo” on the receipt for future warranty, trade ins or open box. My last set was 15k and were as brand new for 10k.

it allows me to build a better system cor less and when i sell or trade the loss is much more palatable.