I have to agree to a significant extent with Mike S.'s assessment, adding that their prices are a serious rip-off. The staff are usually friendly with me, but they always seem to want to engage in some kind of right-wing conversation, despite my repeated attempts to subtly signal that, 'yeah, thanks but I just want to be going'. The last time I was there they charged me $10 for a 50' length of paracord (the market value is about $5). Another indicator of their markup would be the price for those basic foil emergency blankets from Coghlan's: MEC on King St. has them for $1.75. Central surplus wants about $5. For a big piece of paper-thin foil.
After bringing up my purchase, the woman behind the counter wanted to keep complaining to me about NAFTA--god, how old is THAT political chestnut?
Bottom line: The only surplus store downtown, but avoid it if you can. You'll pay too much and possibly be creeped out by the overly opinionated staff. Maybe try save-more next to Moss Park.