It wont do much if you don't have central AC. What it will do if anything if change the air quality in your home, but wont dehumidify in the summer months.

This is incorrect. It will do A LOT, especially if you live in an area that has cold long winters and not so hot summers (upstate NY). I don't have central AC and don't need it in the summers because the summer evenings are cool, just open the windows at night and close them in the morning. Plus we just use ceiling fans if the evenings get hotter than usual. Much more energy efficient than wasteful central AC.
But the winter is when the HRV really pays off. No condensation on the windows or in your wall cavities, fresh air in your tight home, low humidity (and I have an indoor pool!). I keep it around 35% in the winter. I love it and wouldn't be without it.
I bought the smallest Honeywell HRV unit and installed it myself (with help from friend). The unit was around $900 and the other material (ducts, wall control etc.) came in around $300. I can't imagine what labor would be since I did it myself, but it was hard work in the attic where the spaces were tight. My home is around 2200 SF.
I highly recommend it. Good luck!

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I too have a very tight place, 1800 sq ft in central New York state. I suffered through two winters without an ERV. The terrible quality of the air in the winter was not terribly obvious . .. UNTIL I installed an ERV. Summer was not an issue due to no A/C. If you have A/C and use it a lot; then an ERV will help you in cooling season as well. In this case; the ERV will also swap humidity which an HRV will not do.

I have radiant in-floor heat, no A/C; and therefore NO circulation system as such. By figuring the right location of unit and ducts; I'm able to use a stand-alone unit, attic mounted; which pushes fresh air into the great room at one end of the place . .. sucks the "dirty" air out of a bedroom at the other end of the house. Nice, flushing action. I've got it on a timer . . runs to give a complete air exchange every ~ 4 hours. My unit was a Renewaire brand; believe it was about $600 5 years ago. Probably spent $100 on ducting etc . . labor myself. Well worth the money / effort . . . WELL worth it.

Try to keep intake and exhaust ducts approximately equal lengths to get best overall air flow. I used insulated flex duct; my runs were fairly short . . and the CFM capacity of the unit was a good bit more than I needed . . so getting max out of it was not important in my situation.

No clue what a "professional" purchase and installation would cost . . . . . in the right situations there's not a lot of skills required to put one in . . .

Bob

Don't know if the OP is still interested, but since this thread came up again I will say that we just had an HRV installed in our new build (3000sqft)and it cost $1900 in addition to the heat pump, furnace, and ducting. FWIW

Laura

rcmjr, we're looking at a Renewaire system too, here in Maine. I wonder if you could give me an idea about noise levels when the unit's running? We've no attic or basement, and will have to mount the unit in an inconspicuous corner. Right now, the only noise in the house is an intermittent refrigerator, and cats hollering to be fed. Would hate to shatter the silence with a loud fan.