Speaking as someone who makes his living evaluating businesses and business opportunities I think Brian's and M102404's assessments are pretty much bang on. There is no margin in running a field in this sport and even retailers don't make substantial margins in this business. The market in this sport is not the yupee crowd that spend $5 on a mocha latte at Starbucks. This is a bring your own coffee in a thermos crowd or maybe splurge for a Timmy's, that's not a bad thing just a confirmation that folks don't spend money frivolously in this sport, money goes into gear so a retail outlet that is well stocked and reasonably priced might give you some advantage but you won't make any money in running games for all the reasons mentioned by Brian and M.
But if you go forward I wish you success.
I understand the attraction of such an investment as I have contemplated it myself but if you really want to do this I wouldn't do it in the GTA too much competition from "communal" fields. You might want to consider something well outside the GTA.
JIHAD...works both ways