For the patellar luxation, you can benefit from normal neoprene support braces (with the circle in the middle) found in your local pharmacy stores.
As for braces for ACL, MCL and others, CTI's products are hands down the best option for wakeboarding. If filing a claim for insurance isn't an option, the CTI OTS braces are excellent for off the shelf protection without consulting an ortho. Here's a random link I found to them for sub $500 : http://www.amazon.com/CTi-Sport-Knee.../dp/B005PFTO34
I'm speaking from 15 years on the wakeboard, 2 ACL reconstructions - one in each knee. I've owned CTI Customs and the CTI OTS. I lucked out last winter and won the bid on two used medium CTI OTS's off of eBay for $200 shipped.