About 15 years ago I had purchased an airless sprayer and painted my house...more recently (last year) I used a rental machine from Home Depot and helped one of my clients paint one of his rental homes. I would say the rental one was the better deal by a long shot. Once the house was "prepped" we knocked it out in 1 day...the machine rental was very reasonable.

http://homedepotrents.com/diyTools/paint_spr...

I'll second that and the same goes for a pressure washer. Rather than buy a cheaper, inefficient model, rent one that works nicely once or twice a year and you wont even have to store and maintain the thing.

And I am also with them so put me in for three! I have a high end Graco unit. I use it to spray mostly chemicals when I do mold cleanups. I rent almost all of the time. While I do not use the big box store rentals. As they have a tendency to not work quite as well as those rented from a smaller mom/pop rental store. It is really a great way of going. Cleaning and storing these units really can be quite a challenge. ...»