I installed the Dynon EFIS in my Longez several years ago. Overall cost is as listed on their site. Installation is easy as long as you can read. The installation kit which you can buy from B&C for 90 or so dollars makes all the electrical stuff real eazy.
I am currently getting a Blue Mountain EFIS G3 which is a little more cost (~3000) but does more. In addition to the attitude, heading, pitot static, turn rate that Dynon gives you, the BM G3 gives you an HSI, GPS (moving map) and will feed in ILS.