What kind of riser do you need/want?
Cut or no-cut? No cut blocks give you 1"-2" rise without cutting your bars to pieces, and can re-use your stock control cables. Cut ones require you to permanently cut your handlebars and *may* require longer cables.
How much rise and / or how much reach back do you need?
If you can find them used, Heli-bar risers are no-cut and give you 2" up and 4" back.
Can Am riser blocks are still available if you only need a little rise.
https://www.ebay.com/bhp/can-am-spyder-riser