Theres a few dozen around town, some (or most) growers I know send there samples to labs in CA.
Near your part of town;

Chandler Analytical
571 N. 54th St.
Chandler AZ 85226
480-963-2495

MotZZ Laboratory, Inc
2109 S 48th St, Suite 101
Tempe AZ 85282
Ph: 602-454-2376

Aquatic Consulting and Testing, Inc.
1525 W. University Dr, Suite 106
Tempe, AZ 85281
480-921-8044

Our soils here in the metro Phoenix area usually have a pH of from 8 to 8.5, with almost no organic matter. In large areas it is impossible to reduce the pH but if you are planning a vegetable garden or small planting areas for annual flowers, you can amend the soil in these locations. Otherwise, there is no need to try and incorporate amendments into the rest of your yard.

There are hundreds of perennial shrubs, groundcovers, trees, etc., that are native or adapted to our region and will thrive here. When planting these just use native soil as the backfill. For a free full-color booklet on plant choices, contact the City of Chandler water conservation at the link below.

If your question deals with vegetable or annual beds, you will want to create a mixture of 1/3 native soil, 1/3 mulch and 1/3 sand, pumice or vermiculite into a 12 inch layer. Because organic matter disappears in our soil after 6 months to 1 year, you will need to add 4" of compost or mulch to theses areas once or twice a year. More information on when to plant vegetables or flowers can be found at the University of Arizona Maricopa County Extension web site at http://ag.arizona.edu/maricopa/garden/html/pubs/pubs.htm

I hope this helps.

Here is a link that might be useful: City of Chandler landscape resources

Where I live in Phoenix toxins from the sand storms blow pesticides and weed killers into my yard from my neighbors yards. The soil is toxic. You're not just dealing with depleted soil in Phoenix. You're dealing with toxins being blown into your yard from agriculture, and neighbors who are dumping chemicals into their soil. I made raised planter boxes with organic soil from big box stores so I could grow healthy plants, and removed the dirt down to six feet where I planted trees and replaced the depleted dirt with good organic soil, rock dust, and compost. Big box stores will have spring sales in April, and that is a good tome to invest in your garden, and grow plants faster and stronger than what you see on the properties around you.