I understand wanting the harness, for looks, or an eventual track day, whatever. They are incredibly inconvenient for street use, as previously stated. Guaranteed, you will NOT ever use them, for street driving. I speak from experience, I have a Schroth harness in my car, that goes largely unused. I do want to track my car, so it will see some use, someday! Anyway, I don't have a roll bar, as the only one I would put in is the old Saleen style, that are no longer available.
You can get harnesses from various manufacturers that bolt in, using your stock seat belt bolts. I would highly recommend getting a clip-in system, which replaces your stock seat belt bolts with heavy duty eye bolts, so the racing harness can be snapped in and out with the spring loaded c-clips. You will need a mount for the submarine strap, that goes to the center front of the seat. Steeda makes a very nice mounting bar. that bolts right to the factory seat bolts. The only place I have seen them for sale, is Jegs, and eBay/Jegs, for like $60. I think the Corbeau bolt in harnesses sell for around $150, and come in colors. I went with the Schroth, which was only available in black, because, IMO, they make the best safety harnesses available, used by Nascar etc. Just an FYI, if you use the bolt-in or snap-in harness, you will need to cross your shoulder harnesses, due to the increased length from the rear seat belt bolts to front seat location. The Schroth importer, located in Massachusetts sells all of the necessary hardware, for whichever harness you decide to use. If you have any specific questions I would be happy to answer them!
Schroth Racing Harnesses