I suppose that could vary widely depending on where you are at. I think prices here in the US are running around $0.45 per lb, or $20 per kg, in US dollars. Give or take maybe 10%. That's for US sizes as well. Oddball thickness will run the price up somewhat. Thinner plate will be a bit more than thicker plate.
Due to tight supply, prices are up, and mills may be reluctant to quote prices