Yarn, so much yarn

I am trying to decide which yarn to use for my Union Square Market Sweater.

On Yardex we can search for gauge and content a huge database. And I love the fact it gives the MRSP as well.
So, now that I have the exact gauge, fingering weight, 169 yarns to choose from, but only 6 with the exact gauge of 27 sts = 4".

I am intrigued by Cashwool - anybody ever used it? Expensive, though, and not easy to find.

Oh, and if you register with Yarndex, you can save your favorite yarns so that you have them stored!

Gauge of 26 sts = 4": 34 yarns.

Cherry Tree Hill Supersock Solids is a dream to knit with, Rowanspun 4 Ply is an economic choice - and Jimmy Beans has it on sale too!

Gauge of 28 sts = 4": 87 yarns, I'll never pick one!

Oh, look, RYC Cashcotton 4 Ply, that would be less then $50! Or RYC Cashsoft 4 Ply, even less!