255 is the largest I would on a 8.5j wheel. Anything bigger and you would start to get pinch. The car would handle like a paraplegic dolphin.
I can't remember the weight of the Rays off the top of my head, but there is a thread somewhere on the forum. probably in the FAQ section,.
Sets regularly come up for sale. Normally around the £400-£600 mark depending on condition or the wheels and if fitted with tyres.
The 5 spoke rays in 18 and 19 guise are sold as "Nismo" wheels. And come up very rarely, and I think are in excess of £1000 a set when second hand. Though it has been some time since I seen a set for sale so I could be wrong on the price.
As I say, they are pretty damn rare second hand. But can still be purchased new I believe. They used to be £1800 for all 4 (without tyres).