I've made some racks for my DRZ. The problem I had with the ones off the shelf was A. The cost and B. I've got a B&B rear rack which shares the same mounting point of pannier racks. So here's what I did:
First I drilled an 8mm hole straight through the mounting point on the B&B rack to run a bolt through to mount the pannier racks
I had 2 X regtangles made up at the local steel centre of 10mm solid round bar - 200mm x 300mm as the frames then I welded some 25mm x 6mm flat bar as required. I used fairly hefty bar for 2 reason, 1/ strength and 2/ I've only got a stick ark welder and I'm ok welding thick metal and figured I couldn't blow a hole in this stuff
I used the mounting tabs that are used to bolt the side covers on with some spacers. I run stegz pegz and was still ok.
If you are wondering why I put the bar across the top it's so I can use it as a tie down point for a swag or bag across the top. The B&B rack is useless for tie points.
All up cost was $65 for the regtangle frames and the other steel (which I've got heaps left for next project) from the local steel centre.