I'm not sure about Kansas City for pricing as I'm from Minnesota - however, that being said, in my area the answer would be "most likely" buying an existing place and remodeling would be cheaper with some of the home prices.
Take an look at what the average land cost - lets say the lot/acreage whatever you're looking at costs $50,000 (just using a number) then consider driveway, landscape, well/septic if needed and add that number on top. Then look at what you would want to build such as a 2 story home with 4 beds and 2 baths (should be able to look at new construction and get an idea of cost or ask a builder) add that to the lot then pad in some extra for all the things that will certainly be added on during the process.
Next take a look at similar style homes on similar style lots and consider the changes you would need to do to get it like you want - in my area typically the remodel would be less expensive but looking at it this way should get you closer to whats best for you. Good luck.