I have no idea about any Tempe preschools.
Mine have attended preschool in the Kyrene School District in Ahwatukee and this is our 4th year. We love it! My sons have need Speech and Language therapy and they get this for free in class. Half of the classes need developmental assistance and the other half are "typical peers". For ones that need assistance, it's completely free for preschool and a paid tuition for the typicals. It also is a very good step for going into Kindergarten with the Kyrene schools because their is interaction with other grades at times and also library times. The classroom is also set-up very similarly to Kindergarten with a "smart board", cubbies, education, and snack time.
I have also heard very good things about God's Garden and Ahwatukee Preschool.
From what I've heard the cheapest tuitions are with Kyrene and Ahwatukee Preschool.