Even if your confident in your abilities, I would still try to find a proper paint booth to use for painting the car. I've seen many people do DIY paint jobs in booths like that, and honestly some have come out well. Even my AutoBody Teacher has primed cars in his garage.
Saying that though you need to consider what can go wrong doing a DIY paint job. A paint shop would be happy to make some money on a day they aren't open for someone looking to paint their car themselves.