You might want to contact Maxmoto in the bay area. They are the US distributor for Remus exhausts. I got my set of spacers from them for, IIRC, about $20 or so. It comes as a complete kit with the brackets and the bolts. I was definitely worried about it at first, but I've had mine for a few years and have not had any problems with breaking tabs off or brackets cracking. I did definitely warn my wife to avoid putting much pressure on them before I started using them.
I think there's also either a DP or FBF part that replaces the whole footpeg assembly for the highpipes, but it's a lot more expensive and puts the passenger's legs in a very crouched position as they don't really extend down at all. Really only look to be good if you have a girl who's about 4'7" or shorter.
But if you are handy with a welder and want to try yourself, the spacer bars are 80mm long with the H-bar roughly halfway in between. One thing to note, however, is that the spacer bars are ground at an angle on the end where they connect to the bike. I don't know the exact angle, but it's about 5-10 degrees so that the brackets have a slight upward angle when looked at from the rear of the bike (if that makes any sense). But if the kits are still available and as cheap as I remember them, it's just not worth the time and effort to make them yourself.