There are a number of candidate race fairings from the late '60's and early '70's that would work well on your bike.
My replica Yamaha TR2 (the TR2 was built from '68 to '71) fairings are used by a number of CB350 vintage race guys. They fit great and are "period correct", styling-wise, if that sort of thing is important to you.
A friend is going to use a slightly later model Yamaha TR3 road race fairing that I built, on her CB360 street bike. The Yamaha TD1 fairing, aka "the fairing that launched a thousand race bikes" will also fit and was the one I was looking at for my CB350 project - I really dig the classic '60's look of that fairing.
Depending on what headlight you decide to use, you may have to cut a hole in the fairing - I offer this service to my customers and also add additional plies (layers) of fiberglass in the area of the cutout for extra strength. An alternative headlight mounting system could be similar to what the endurance racing bikes ran in the '70's - an alloy bracket bolted to the front of the fairing and one or two lights mounted to the bracket.
The physical size of the older Yamaha race bikes was a lot closer to the street bikes of the day, so race-derived parts are more easily adaptable than something newer. Point in case; one of my friends wanted me to build a late model ('03) TZ250 Yamaha fairing for his RZ350 and except for being too narrow, too short and basically too small all around it fit fine LOL.
Half fairings also work well; I've sold a number of them to CB350 and 360 riders.
As far as cost, well, what is expensive to you? A couple of weeks ago I was picking up a few bits at my Honda Powerhouse and the guy ahead of me was forking over a wad of money - looked to be about a grand - for a dorky little windshield and a few bits of black plastic (not fiberglass) for his street bike.
I think full (race) fairings on street bikes look pretty neat - I've already got the Vesco fairing built for my RD350 café and the rest of the bike is still on the bench, all apart, LOL #2...
Good luck on your quest. Pop me an email if you need photos, advice, whatever.
Pat
pacomotorstuff@cogeco.ca