Most economical would be to head to the TTC and get the Lynx bus to SW from there. It's about $1.50 pp, each way...exact change please. And you do have to tell the driver you want to get off at SW.
You can book Mears shuttle to get you there as well, but it isn't nearly as cheap. A taxi van might be a good option for that many of you...or a towncar service van. Probably run about $60-70 r/t.