There are some great deals out here, and lower taxes than Cook county.

So let's say you were to buy a $200K property in Cook County, IL on May 30, and the property tax was $8,000 for the year. 

It was next to a propane gas & welding facility that was at one time a gas station.

Some will also have minimum standards for homes built, such as minimum sq ft of living area, maximum height, etc.Another thing to consider is building a self-storage facility - again, if zoning allows it. 

I see a void that is necessary to be fill, but also an opportunity to build a commercial space for an urgent care facility that is built to their needs, however I don't know how to go about contacting a company in this space.

I know of 1 new storage facility being built right now.

One notable company is Intel in Chandler who just finished a new fabrication production facility, a $7 Billion investment said to be the most advanced in the world, adding 3,000+ high-tech, high-wage jobs.Many schools in the vicinity are regularly ranked among the top in the state, there are numerous opportunities for great shopping, restaurants, coffee shops, entertainment, parks, etc.The rent/price ratios and cash flow/appreciation one can achieve especially in Gilbert (next door to Chandler) are excellent and I've helped clients purchase roughly 25 homes in the last couple years that fit the same model - relatively new (built in the last 10ish years - newer roof, newer HVAC, etc), reasonable HOA's (around $100 or less - which includes access to a community pool for tenants, front yard landscaping, playground/parks, etc), easy access to freeways, good schools, etc.

Or is it better to pay current market prices on a more turnkey property to avoid having to hire and coordinate fewer cooks in the kitchen?

Cook County side? 

It has a few manufacturing facilities and a college but overall it seems like not a lot is happening there and it is fairly depressing.