Need to replace furnace

I own a duplex rental in Des Moines, IA. One unit (≈1,000 sq ft) needs a full furnace replacement due to a cracked heat exchanger. It is a gas forced-air system and tenants pay utilities.

I don’t have any HVAC knowledge and want to avoid overpaying for unnecessary features.

For landlords who’ve been through this:

What type of furnace should I be asking for? 

Are there any features or upgrades that are not worth paying for in a rental? 

Are there any features that are important to have? 

Roughly what price range should I expect for a basic, reliable replacement?

Appreciate any feedback.