Luke,
Different prices for different races.
Saturday they have 10 lap races and it is more prep time for the cars.
Sunday is just a show. Lime Rock can not race on Sunday due to restrictions.
Monday are the feature races where they actually get the cars being a bit more competitive as compared to just for show laps. I think races are 15 laps each.
Link below will provide better info.
http://www.limerock.com/LRP-Events/vintage.html
As Bob states -- part of the great day at Lime Rock can be the roads getting to the place. Really nice setting. Open access to almost every spot in the facility. Certainly open access to the cars and people working on them if you want to ask questions.