For discount suits, the above-mentioned places work well. Syms, in particular, has a lot in the sub 500 price range, and if you're lucky you can find a Hickey-Freeman or Burberry for 400.
It sounds like you may have to get something more expensive for right now and do some careful discount shopping on e-bay or around the city over the next few month. A basic Brooks Brothers suit should tide you over until you have some time to ship agressively. As mentioned above, if you can find a basic fabric suit on the sale floor that fits, you're stoked. They're pretty nice.
You need basic suits, like solid navy and solid charcoal, or something in those colors with a subtle white pinstripe. These basics from quality makers at deep discount are rare, though you have an advantage not being a 42R.
The Corneliani at Filene's Basement is closer to 500 or 600 bucks, and usually very nice, though lots of exuberant pinstripes around.
You will find plenty of otherwise great suits with blue or red pinstripes, windowpane patterns, etc. in fabrics other than what you need: worsted wool twill.
Lauren by Ralph Lauren have better fabrics than than the Nautica, Hilfiger, or Kenneth Cole, Jones New York, Michael Kors, etc. that fill department stores, but "Polo Ralph Lauren" suits are far, far better. I usually get mine on eBay for 300-400 bucks new with tags. Tailoring is another 100. These suits retail for 1100-1200 for basic fabrics and the standard Polo II cut.