M.R.
Almost twice I have bought my own kiln....b/c they were at estate sales.....but we moved and it was too difficult to commit to that sort of space.
I recommend you shop around on Craigslist or Ebay to see what is out there 2nd hand. Take a want ad out on Craigslist. Check with summer camps who are upgrading their kilns.
I think those new Pottery places are jokingly expensive and I would recommend you avoid paying them such high mark ups to fire your stuff. Perhaps start a monthly club with other interested parties.
How close are you to Leisure World in Phoenix? They have a kiln in their hobbies area? Maybe you can volunteer to help there and get free kiln time??? Just thinking out loud here...
Also remember, once you buy a kiln, you'll need many extras: a special outlet b/c I'm sure it runs on more than a 30 amp plug and there is normally only one to a home for they washer/dryer. Also you'll need a special, sealed and safe room so no one little has any access while you heating and cooling the kiln. There are a lot of fire and electrical concerns to to map out before you make that kind of investment.