i have an '08 45Y and replaced my Raymarine setup with a Garmin setup. for my project i replaced the MFDs, radar, the 2 EVC displays, and the depth readout. i also converted my engine data to N2K so that i could integrate everything. so, i did a bit more than you are here...and i had no autopilot integration since the newer setups won't work with the old autopilot. will be interesting to see how well your old autopilot integrates to your new MFDs as toofast pointed out, the upgrade paths aren't very good.
i also had to have a custom panel made out of starboard since the new MFDs are smaller than the old E120's, but i don't think that was a huge component of the job.
not counting the actual components (MFDs, radar, etc.) i paid for 36 man hours which was almost $4900 including all of the incidentals. so, i don't think $2800 is too bad.
the hard part in my boat, and i assume yours, is that unlike FastMarkA's boat, there were no channels to run the wires easily. you'll have to fish everything through which can be very time consuming, and the openings are quite tight. once all of that is done, the integration and calibration can take a bit as well. personally, i would have done the job myself if it hadn't been for the integration component. there's so much that can be tricky it pays to use someone that has an easy ear into product support.
hope this helps, and good luck with your project!
todd