Diesel engines like this are not for the weekender or somebody unsure about how long you will stay in business. Your return on these investments come in owning and operating them for thousands of hours. Fuel economy will be easily 30% less then a comparable gas, and if you do the regular maintenance you should be able to get twice a typical gas engine life span.
I would love something like this again, but I can't justify throwing away a good running gas engine. Good luck, show us pictures of the final product if you do get it