I'm sure a significant portion of the difference in prices across the nation is related to overhead. The dealer closest to me happens to be in Newport Beach. Their sales dept is on Pacific Coast Highway. I'm sure rent there is much higher than a place like Cincinnati. Just look at housing prices.
Also, Lotus dealers will probably be in more affluent areas whereas Toyota dealers will also cover more modest areas.
With close supervision I guess I'd trust a Toyota dealer to do an oil change every once in a while, but I would still go to a Lotus dealership every now and then just to make sure everything is up to spec.
I know I wouldn't trust my local Toyota dealer with my Lotus. I've had two different dealers at two different ends of CA botch up my mr2 turbo on several occasions. Broken oil level sensor from resealing the pan, replaced a clutch with a bad one, missing or improperly torqued axle bolts, stolen amp while on the lot, leaking valve cover 1 month after having it resealed, improperly reinstalled exhaust, just to name a few.
