Or check on gt5cars.net when the 2J will come again and skip if you can. I was in the same situation as you last week. Had to skip a 2J because I ran out of money (wasted in online UCD).
I'm on the second master list and I only have 21 race days to go (from about 80) for it to appear again, and 60 race days if I skip it now.
There are only 3 cars that you have to watch out for:
Ford - GT40 Race Car #6 '69s (costs 19.6 million credits)
Chaparral - 2D Race Car #7 '67s (costs 12.4 million credits)
Chaparral - 2J Race Car #66 '70s (costs 14.8 million credits)
Everything else is chump change, the next one starts at around 6.5 million credits and it only goes lower so once these three are in your garage you can pretty much relax. It's also good to use gt5cars so that you can anticipate the ones that will require a lot of money.