Anyone else notice the massive change that occurred three days ago to Guild Wars 2? Take a look at these patch notes:
The crafting recipe for Bolts of Silk now requires 3 Silk Scraps.
The crafting recipe for Cured Thick Leather Squares now requires 3 Thick Leather Sections.
I've been buying both items like crazy, while simultaneously watching the price slowly rise beyond vendor values for silk scraps (now up to 14 copper buy order!). Thick Leather Sections haven't moved beyond 8 copper yet, but they certainly will at some point.
Silk Scraps appear to have a lot more room for growth, so even though they've already doubled in value, I still think they are worth investing in. If Thick Leather Sections remain at 8 copper then I fully expect ArenaNet to eventually make Cured Thick Leather Squares require 4 Thick Leather Sections.
We've learned yet again that ArenaNet will work to make items worth more than their vendor value + 1 copper on the trading post.