The Ebay listing is below for the unit I purchased. You will still need the venting kit, that adds about +/- 2" in height. The kit includes the front bezel & a top & bottom vent that provides intake on the top & exhaust on the bottom; as these are normally done on the back of a countertop unit.
As to how much time to complete, I depends of your existing cabinet space & your abilities. As an example, I was concerned with the bottom of the front bezel lining up with the bottom of original cabinet. I installed the top & bottom vents on the microwave & slid it in. To my surprize when I held the bezel up in place, the bottom lined up perfectly. If the bottom of the bezel was below the cabinet I could just raise it, maybe if I had the room. If the bezel had been above the bottom of the cabinet & I didn't like what it looked like, I may have had to replace a lot of formica covered wood. It all depends on the look you are trying to achieve.
I think I had to move the plug in back up a little, but that was about it.
New Kenmore Elite Stainless 1 5 CU ft Convection Countertop Microwave Oven 67903 | eBay