You're welcome. Also, keep a very close eye on your Used Car Dealership. Each time you enter an event , license test, etc. (i.e see the starting grid), you don't even have to start the race the Used car list will get 6 new cars and thus drop the 6 oldest. The dealership holds 30 cars so if you do say 5 races on that Ferrari seasonal the used car dealership will have an entirely new selection of used cars. With some cars being exceptionally rare try to get into the habbit of checking the dealership often, preferrably every 5 or fewer event starts so as not to miss out on any gems that might show up and not return for like 1000 or more days.
I'm currently looking for the Pagani C12S 7.3 and TVR Speed 12. The TVR only showed up once in my first few days of playing and I didn't have enough money for it. The Pagani has yet to show up and I'm into the 1300+ day range.
Like you I was late on getting started playing GT5 and missed out on some great cars that have shown up in the On-line Car Dealership since the game released. I have most now but it sure would have been eaiser just knowing they were in the on-line dealership. So that's the other place to keep an eye on, the On-line Dealership, there you get to see some of the rare cars show up. It typically refreshes every few weeks to I guess about once a month probably.