Assessed values throughout the Milwaukee area (and beyond) have very little connection to what a property is worth to a Buyer. It is merely a way for the municipality to determine what the property is worth for taxing purposes.
I can only suggest that you have your Realtor provide you with comparable recent SOLD properties within the area of this home- Sold within the last 3-4 months. If there have been no recent solds, see what is pending. I know that there are quite a few homes that have no basements in the area, you can usually buy a basementless home for a little less than one with a basement- but you will get a little less when you sell also.
If the property meets your needs, and you are comfortable with it- by all means it is better than renting.
Depending on how motivated the Seller is (your agent may be able to find out a little more about that by talking with the listing agent) you may be able to buy it for a less- all depends on how many other people also see it as a good value. Again - your Realtor is your best source of information, hopefully you are working with them as a Buyer's Agent.
All the Best to you!