I know they are higher than a lot of areas, but not as high as you found. My parents house in Pleasant Hill Iowa (Des Moines Suburb) was assessed by the county at around $180,000 and they pay $3300 per year in taxes.
If you go to
www.iowarealty.com and do a search for homes in the Des Moines area, click on the details of a specific home and at the bottom of the page they will have the previous years taxes. Urbandale has the cheapest taxes I think, and it is a very nice town.
Coming from Cali you will notice the cost of living is extremely low in comparison. It's not just the housing either. I am from Des Moines and live in San Jose, CA. Most everything is cheaper in Des Moines. Gas is probably around $2.70-.80. Here it was over $3.20 today. Groceries are cheaper in Iowa also. A half gallon of OJ at Safeway is like $4.90, in Iowa its probably like $3.00, if that. Schools are a lot better in IA than in CA.
I know a lot of homes in the Des Moines area are assessed by the county for less than market value.