I don't care for it at all, but if you're after getting all the Ferraris, you have to do it, whether now or later.
I'm at the point where the money piles up TOO fast now - I have to find crap to spend it on, including no fewer than a dozen Enzo Ferraris (one in each factory color, plus a Chromed one, a Gold Chrome, a Sublime one, and a Lava Orange Pearl). I've bought every high-dollar car now, so I have to find things to blow a million or two on every time a new seasonal posts, just so I can clear out money under the 20,000,000 cap.
How much is the SP1, anyway? I vaguely remember buying one, but I've forgotten the price.