Are you talking about a groundcoupled heat pump, or one put in a lake, or one taking energy out of the air?
The latter is much cheaper but stops working when it gets too cold outside, while the two previous work even if temperatures fall to -20 C, but they require much more capital, mainly because of the cost of drilling the well.
Heat pumps of different kinds are used extensively in Sweden and would be considered a rather mature technology over here. Heat factors are usually about 5 (that is you get 5 kWh of heat for every kWh of electricity inserted into the pump) as long as the medium you take heat from is warm enough. Another good thing is that can run it backwards in summer so you don't need air conditioning, even if that shouldn't be needed in the first place in Michigan.
It's important to know how much heat you have in the ground/lake. If you overestimate it the well will produce too little heat and if you underestimate it you will make the well deeper and more expensive than needed.
An interesting way to change the capital cost requirement is to drill a more shallow well but adding a solar heating system. This means that solar collectors are installed on your roof and recharges the well with energy during summer which means there is more energy to take out of it in winter. The well becomes cheaper to drill but you get the added cost of installing the solar system. It's the one solar technology that can actually make economic sense.
If you get a heat pump (and I generally think they are a good idea), make sure you use a big well-known company and can get a refund/free repairs if the system breaks down within 5-10 years, especially if you don't take the cheaper aircoupled heat pump. These things have a tendency to break or not to deliver the expected capacity if they are done sloppily.
One of these quality companies is NIBE. They don't sell their products in the US, but they do sell them in the UK. I'm sure you can mail them and ask them what companies in the US make quality equipment. They should know.