Busa bars are 7/8ths. Not sure if a cbr is the same, would be easy to measure.
You'll need to add a brake fluid reservoir, cheapest way is a used OEM res, ebay 15 bucks.
New they are anywhere from 330.00-365.00 depending on where you purchase. I would take it if it's in working condition for 200.00, a steal would be 150.00 or lower.