What Good and Affordable Alternative Power Source Would You Recommend?
Good and affordable are both relative to many local factors. Your best bet is to look around you and see what fuel source is abundant. You'll also want to think about how often/long that resource is present during high power use periods as you'll need to store the power for later use which can rack up the price.

There are areas of Michigan that are some of the cloudiest around and so solar may not be a good choice for the amount of radiation present. Add in the shorter days in winter and you compound it. However other areas are close to wind tunnels during the day (lake air movement) and so wind could be a good solution since power use would be lower in the middle of the night when the winds die down, saving storage costs.

If you are surrounded by fast food joints changing your generator to run on frying oil or biodiesel may pay for itself quickly with the low cost fuel supply. 

Once you decide on what is locally abundant, then turn to google (or this board) to see if there are low-cost DIY options or suppliers in your area. Importing equipment might wipe out any potential savings, though if you are doing this as a business expense you may be able to write off some things or look around for grants/rebates for "green businesses".