Fit first, brand second.

Know your correct size.

Then starting looking at CL lists outside of Manhattan. An old friend lives in Manhattan and was only looking in Manhattan proper. He came up with quite a few overpriced, beat to death bicycles.

He widened the net and ended up finding a very nice Pinarello for $450 a couple of years ago.

It was located in Buffalo.

The seller was willing to ship as well.

It can be tricky buying a used bicycle w/o looking at it in person, but it worked quite well for him.

I've purchased over a dozen bicycles via this method and it has worked out ok. I was amazed that some made it to me due to poor packing regimens, but that's another story entirely.

Don't forget, we have a facilitator thread started by Khatful, so I would try that angle as well.

Fwiw I've ridden a couple of Olmos with Columbus SL tubing and they were just fine. Handled just like I thought they would.

Good luck.