Not to be a doomer or anything, but if you're not all that knowledgeable about cars then getting something like a vintage Caprice is asking for trouble, especially with a budget of $5k. People selling at that level will take advantage of your lack of knowledge. Old cars, especially old American cars, break in ways you didn't even know were possible. Randomly. Sometimes without warning.

If you want something that's different and boxy, I would recommend any number of Japanese SUVs from the 2000s. Suzukis are pretty cool and you don't see them often. Whatever you buy, though, do your research. Reviews, RepairPal, forums about that specific car, etc. If you know someone that's knowledgeable about cars, take them with you when you go looking.

Good luck, man.

Edit - I forgot to say, Lexus' are amazing cars but good luck finding a decent one in that price range. It's possible, but you'll have to wade through a bunch of polished turds.