I have been searching too. So far no luck. The only half decent place I found so far is ElectroSonic up at VictoriaPark and Steeles. They sell Neutrik NYS352G RCA male plugs and 100' spools of Belden 89259 coaxial cable which can be used for various DIY audio cables. I think they carry silver wire but again only in 100' spools and may not always have it in stock. I thought 100' was alot but after making some 89259 cables for myself and "lending" a few to friends, it was all gone. The only bummer is they are an order desk setup, so you have to fill out your form, wait for up to 30 minutes, and i think orders under $20 are dinged with a $5 service charge. There are 2 other electronics stores in the area (Active and Sayal) but they carry cheap stuff.
There is Supremetronic down on Queen St. W. which carries a number of RCA plugs but I don't know if they are high quality. There are a few hi-fi stores that I've seen carry a few DIY items but nothing spectacular and they are scattered all over the GTA (Kromer Radio, Tabangi, American Sound).
Other than that you are stuck with mail order. I've bought from Take Five Audio a few times and they carry nice RCA plugs like Cardas, WBT, Eichmann and also many types of wire/cable including silver. Best of all they are Canadian (MountForest, Ontario) so they list $CDN and you don't have to worry about paying duty although GST and PST apply. I usually get my stuff a few days after placing an order by Canada Post Expedited Parcel.
Hope that helps.