Why don't you try the Holt Renfrew outlet at Vaughan Mills? It's a bit of a hit-and-miss up there, and whilst they've a limited selection for men as compared to women, there are wonderful bargains to be had. They carry all the major designers of course, and at your price range, you could easily pick up any of them--or even 3--since they're discounted at up to 90-percent off retail, at times, assuming that you can find your size.
Other major designers are also up there, including Boss (note: I loathe recommending designers in general, being over-priced for what you get, but a Boss at 99 bucks isn't exactly over-priced, assuming once again it's sale time, and they have your size, etc.). You'll also find H&M, Winners (Canada's version of Marshall's), Banana Republic (I think), among so many other outlets up there, all at deep discounts.
You might also try the Marshall's chain, which is now in Toronto. Again, like Winner's, it's a hit-and-miss, but they carry RLPL, etc., or so I understand.
In terms of tailoring, keep in mind that it's not a big deal for experienced tailors and/or seamstresses to take in a jacket, provided it fits you well in the shoulders, etc. Sleeves can likewise be adjusted.
As to your budget, don't be so quick to rule Rosen out; if you're willing to double your budget, you might be able to pick up a Coppley or even a Samuelson when they're having a sale--they've some nice slim fitting suits, and Samuelson is quite nice, really (i.e., canvassed, not fused). From memory, I think Samuelson runs about 1200 for a suit reg price, about 900 or less on sale, but that's for the whole suit--and during a trunk sale, can have one made-to-measure for a very affordable price and far better quality than "designer". If you're ok with used, might even do a search here on the B&S boards--you never know, and worth looking into, I think.
Otherwise, I highly recommend Vaughan Mills; an Armani blazer can be had sometimes for as little as 99 bucks. I kid you not: check it out, but remember it's a hit-and-miss up there, as noted.
EDIT: here's a link to Vaughan Mills for you, which includes a mall directory: http://www.vaughanmills.com/