It really depends on how much you shoot. The best way to buy a cam is to consider yourself your most dependable customer - here my wife and I account for about 50% of "rentals". We charge clients the same rate at which others rent from us, but being able to test and experiment on a whim is priceless.
In Montreal Epics are price controlled by a certain big rental house with "connections". This is a good thing for all as it keeps the market from bottoming out to the level of the most desperate loser in town. Rent an Epic under $700 (without lenses - just camera media, etc. based on week counted as no less than 3 days) and you first get a warning call, then a "visit" from the kind of people you do not want to have visiting you. Nobody rents under $700 (not for long, anyway) and so that's simply what producers pay, more for the luxury of a big rental house with lots of support and back-ups (whereas we can only offer a Red One MX as a back-up if need be). $700 is not crazy for an Epic package. Everybody wins.
Other cities are like that too, in Italy for example. I hear New Orleans is like that for everything, even for Steadicam ops.
Anyway, banks here would never lend you the money to buy a cam, and so few people own as you'd have to have the full amount in cash. Quebecers are also culturally leaning toward renting, even for housing. All this to say, this is potentially a great town to own an Epic if you're willing to make the calls and build relationships, and have lots of friends who are PMs, producers, etc. to get you started. Other places vary wildly. I could see the advantage of having one of the only Epics in Minneapolis. They do shoot a lot of stuff there.
As a last thought, doing promo of your gear rental takes time and effort you might rather spend actually shooting.