I wouldn't go the DIY route with spray cans. Spray cans don't spray as fine a mist as the paint guns, you'll probably pick up dust in the paint, and probably make a mess you don't want to clean up (been there). Out of the other two, I tend to shie away from Maaco, but they may be better quality up there than here. Will they both take the bumper off to paint (a must)? Taking the bumper trim off as well (as opposed to taping off)? Do the shops have downdraft booths (prevents dust in the paint)? Does the price include clearcoat (not an integrated one, an actual layer of clearcoat paint)? If the answer is the same for the two shops, then I'd go with the cheaper one.
If you do decide to try it yourself, put the spray cans in hot water for a few minutes before using. Start spraying before the part, keep going in the same direction past the other side, then spray back across, etc. You can wetsand with high grit sandpaper (1200-3000) between coats for a real smooth, shiny end product, but that will take a lot longer.
However it's done, remember not to wax it for a month or so for the paint to fully cure. Good luck

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