Most expensive materials?

If you want to pay a lot of money clothmakers will find some way to deprive you of your money. In addition to more and more finely spun cloth, often making suits that are simply too delicate to wear, there are novelty cloths with diamond dust, gold dust, or lapis lauzuli sewn in. I know of one suit made with an 18K gold pinstripe. Really, though, if you have that kind of money just give some to me.

This one probably be in the top 10. H&S

Geez, and I thought having a monogram on a shirt was a little pretentious.

While that's got to be expensive, there are now so many novelty super 200s (give or take some super 20s), vicunas and vicuna/cashmere blends that the humble super-wool/cashmere monogram stripe is likely to look reasonable in comparison.

Far as I know, Guanashina's (made by Dormeuil, I think) the most expensive there is without including cloths that have lapis lazuli, diamonds or gold sewn in. In CDN figures I think one of the prices I saw at a local tailor was in the range of 3500$ per yard, if I remember correctly. EDIT: Here's a nice link. The images used to be up, but not anymore it seems. Some of the PDF files at the top of the page do seem to be working, though. http://www.richardandersonltd.com/press/

Moxon fabrics cost up to 3000 BP per meter. Vicuna is also damn expensive. The H&S Initial Cloth is not the most expensive. I consider it vulgar and, if self-color initials are chosen, highly unnecessary. I never even have my shirts monogrammed.

While that fabric above is pretentious, let's not sink into reverse snobbery or resentment.  Personally, I always monogram my shirts with my family coat of arms and other heraldry.  

I have seen aligator skin made into suits.