Bar risers go from about 30 quid....the touratech ones for the 650 are £33 but there are various types......I'm sure there are many more out there but I've never looked for them for a 650.
I'd doubt that you can't turn the levers aropund the axis of the bars without causing problems with bleeding...the system should be sealed in the pipes and cylinder rather than anything to do with the angle of the lever but then again, I've only had an old Funduro 650 so I've no idea about the new ones....but I'm sure someone will be able to clarify that either here or on the 650 site.
I found them a really good add on.....made a big difference to my comfort and even if they don't, you're not going to lose more than a couple of quid by buying and trying then selling here if they don't work for you
The other aspect to look at is the spread of the bar and the angle that your wrist makes outwards to the grips from the arm.......some people swear by Pro-taper bars that change the angle but I was happy with mine so didn't bother.....if you want to do some reading on it though, do a search for Ricardo Khun, a bloody nice bloke from ADVRIDER who posted here a lot about his bars......the mutt's nuts but I don't think he's doing them any more.....he's a real expert on ergonomics though and he posted some interesting stuff on it here a few years back..it'll still be here
Good luck with it
Bill