I'd say that the price you paid for TSS wasn't terrible. Wasn't a deal, that's for sure. But as I've seen em sell for that same price range. And considering how infrequently that pops up the amount of time you'd have to spend hunting for one most likely wouldn't outweigh the slightly lower price you could possibly eventually find.
Enjoy yer cart.
And I'm not sure which is the last car you're lookin for, but other than a few of em they should all pop up frequently enough that some patience is all that's needed for a decent deal. WJ & TSS are a couple of em that pop up and are usually gone immediately but you've already got those. Other official carts that aren't so easy to grab would be P&N, Ganryu, Pleasure Goal, Pulstar, Sengoku 2, Nightmare in the Dark, & Iritating Maze. But the rest of em usually come up often enough that a little patience and you'll find one that suits your price/condition needs.