I'd buy a Case IH dealership and would add Antonio Carraro and Bobcat as specialty lines or some other offshore specialty tractor lines. An established Case IH dealership would likely already have a worthwhile existing customer base and business volume. I would also bring in some interesting implement lines from Europe and some of the niche implement lines made here in the USA. I'd also have the business geared-up so that each month it broke even on the shop work and parts sales. This would give the business a natural orientation towards good customer service. New and used equipment sales would be the owner profits.
As a young man, I worked for a successful commercial business machines dealer (typewriters, adding machines, cash registers) who ran his business to break even on the service and parts sales volumes. It kept the business close to and in-touch with its customer base. It also did considerable new product sales to its customers. Because the business carried itself on service and parts sales, the new product sales were very profitable and fell straight down to the bottom line. It has been my impression many successful tractor/implement dealerships utilize the same thinking as the above described business owner I worked for back in the 1970s. However, unlike typewriters which have become obsolete, the tractor business is alive and prospering with what seems to be a growing back to farming trend for small acreage (less than 20 acres) part-time farmers.