I would like a ball park figure,just to see if maybe i can afford to have it installed.
 I am now burning fuel oil and it is killing me,here is what i have, 25 yr old house fairly well insulated forced air heating, central air 3000 sq ft. 4 inch well with good water supply,pond for dumping sandy ground.
 The problem area is that the basement is finished off,with drywall on the ceilings a real problem for changing the duct work. I do not like the idea of tearing it all down.
 There may be other problems that would that i am unaware of. the cost for one, i am retired and on a fixed income but i have got to do something before i freeze to death.
 I live in Michigan 25 mi. south of Lansing,fuel oil now over 4.50 per gal.
 If i can afford it i will go geothermal,i need a need a ball park number,before i can get to excited.
 Thank You for any input or ideas.

Hi, I read your posting and am surprised that no one has replied yet. I'm replying as someone who was in your shoes. We have a 1400 square foot 70 year old home that had forced air heat running on fuel oil. We've done a lot of renovation and have updated insulation, windows and siding. In January we decided to look into Geo as the price of fuel was just starting to really get up there. My first stop was our local electric utility company. They had rebates tied to Geo and also suggestions on reputable installers. We contacted all of them, three came out and promised bids, two actually did bid. We looked at two different systems with two different prices based on very similar data from the installers. We had an energy audit done by the electric utility and the auditor did a great job of explaining pay back and going over our bids with us. We live in northern Minnesota and have enough land to do a closed loop horizontal system and had it retro-fitted to our forced air ducts. We had to do some modification of the ducts which ended up costing us $400. Our final cost was $16,000 but our payback is estimated to be 5-7 years based on a fuel oil cost of $3.25 per gallon, so we think it's going to be sooner than that. Our heating costs since installation have been approximately $40 per month (Feb, Mar, Apr) so we're ecstatic about that. We decided that this was a way to reduce costs going forward to retirement in 10 years. I'd start by calling your electric utility provider and see if they have any incentives and referrals, then I'd contact dealers in your area for estimates. I got my first rough estimate online on a local installers website, they had a site that you could enter in basic information about your home and get a rough idea on cost and feasability.

Try the IGSHPA website for trained installers near Lansing. I just did but that part of their site seems to be down - maybe try tomorrow during the day - perhaps it'll be fixed by then.

Since you already have ducts for heating and cooling, perhaps you'll be able to get by with minimal duct rework - make sure whoever you contact for proposals runs ACCA Manuals J, D and S calculations. If they look at you funny when you ask for those, find someone else.

To evaluate payback you'll need to know your cost per kwhr of electricity. Find out if your utility has a different (with luck, lower) residential rate for electric heat, and that a geo heat pump qualifies (it should), and factor that in.

the cost of the equipment is relitavely minor compaired to drilling the well field, and that depends on your site.
for round numbers figure 200 linear foot of well per ton of refrigeration.
For system cost ballpark $2-4k per ton.