£12.50 to fit is a bargain. It usually takes me 1/2 hour just to find the right size spanner!
I got my H&B bars from Motobins in May this year. They were having a "10% off everything" weekend. Worth a look to see if they're doing a similar offer in the near future.
The trick when fitting them yourself is not to remove more than 1 bolt from the rear subframe at any time. If you remove 2 or more bolts the subframe will move out of line with the holes and you'll have to jack it up into position to get everything to line up again.
Also, be prepared to enlarge the rear holes on the engine bars to get them to line up.
I went for the black ones as they are easiest to touch up when (not if!) you scuff them. A bit of black enamel paint and they look good as new. It would be harder to fix scratches on the chrome ones.
What I'd like to do next is fit something to protect the tank. The Adventure tank is wide and looks like it'll touch down if the bike rolls over the engine bars. Something like the tank/beak bar on Paul's picture. I may get someone to weld up a bit of bent tube for me, as a project for the winter.