I bought my steel enclosure on ebay from Electrical Replacement Parts
By far the best price I've found, and the box will survive a nuclear blast.
They've got stainless too if you're a bling whore
Sort of related, I got all my DIN-rail mounted stuff from Tier1Automation
Really good prices, free shipping, and you can buy just 1 of something if that's all you need.
That was my only complaint with AutomationDirect - I don't need 50 pieces dammit!