We got a couple of quotes from different companies, all of which had received good reviews on Homestars (a great website where clients can leave feedback for home-related service providers). I was shocked by the price difference among the quotes though--the highest was $1600 and the lowest was $400! Both were going to do the same stuff, but the higher bidder was admittedly going to do it in a fancier way.
Our attic is about 400 square feet, and we wanted R50 of cellulose insulation (R50 means it ends up about 2 feet deep, it seems). I learned along the way that it is possible to blow added cellulose insulation into your attic yourself (although we decided it wasn't worth the hassle, given the great price we got). Apparently buying the insulation for our job would cost about $300, and there's a machine that you can rent that blows it up into the attic. At least this way if you're not getting any reasonable quotes in your area, you know there's another option available.
If you don't already have one, you should build a "collar" around the opening for the hatch. This is a wall that prevents all of the insulation from tumbling out when you open the hatch. Our expensive quoter wanted to make the hatch hole bigger, install a fancy plastic collar and a proper, insulated hatch. Our cheap quoter built a collar for us out of cardboard, and insulated our existing hatch cover with batt insulation (the fluffy pink stuff).
When it's done, it should look something like this:
And you and your family will be warm and toasty all winter long, and stay nice and
cool all summer long, saving money and energy and the earth all at once!