Yeah, the Markets, I've admitted, were a bad buy. I got cocky because in every game I've played with Grand Markets, getting them all has been tantamount to winning.
Honestly, I think the Treasury stack gave me a distorted view of the effectiveness of my deck, and part of my putting off buying green was not wanting to lose my Treasuries. But also, I thought, "I have a really strong, consistent deck" when really, once my Treasuries became Peddlers, stopped being the case.
So lessons learned (in no particular order):
1. Don't break the PPR.
2. Don't delay greening unnecessarily.
3. You don't always have to buy Silver (or anything) with $3 and in a cantrip-heavy engine anything that breaks the chain is bad. (or better yet, don't build an all-cantrip engine at all)
4. Treasuries can make your deck seem better than it is when the greening starts.