if you're looking for steelcase, just search for metal vintage or steelcase on craigslist. lots of people sell that **** not knowing how rad it is.
also, there's a wicked furniture store at queen/parliament that sells tons of vintage furniture, lots of 50s mad men type ****.
if you want legit midcentury modern, morba on queen is the only place i've found with a well-edited selection.
also, there's a new collective called upside dive (upsidedive.com) that resells vintage finds. they are a new business and thus are very receptive to making their customers happy. i bought a teak bedroom set from them for soooo cheap and i told them to keep me posted on any good finds in the future. i'm sure they'd keep an eye out for any steelcase type stuff for you.
</furniture nerd>