The width and angle of the GS peg is quite common , so there are quite a few alternatives around, you just have to re drill the pivot pin position and bodge, sorry, grind the curve at the end.
It helps if your your local dirt bike shop has a few in blister packs hanging on the wall , but from memory I ended up with a pair intended for a Yamaha YZ , cost less than 10 quid and about 25 mm lower, probably as much as you want if you like to change gear and brake with your foot still on the peg.