I am on the hunt as well for a mid-end brand that comes in at around $400 ish, either with a code or retail price! Would be very interested to hear other brands that RM fans enjoy in that price range.
I like Botkier -- they are a slightly lower price point than RM is now, usually around 500 - 600 and don't usually let you use codes either (I think they have the same showroom as RM, which prohibits the use of codes) but they have a lot of sales.

I have also heard good things about Jenny Yuen (codes allowed!) and Treesje.