Kics- good quality, need hubcentric rings to actually be hubcentric, ~$130-150 a pair plus ~$35 for the rings if you decide you want them. Available up to 30mm.
H&R- good quality, already hubcentric, ~$70-145. Available up to 25mm.
www.wheeladapter.com- good quality, hubcentric (I believe, I know mine were but I did buy them used and it may have been an option), a bit on the pricey side. Available to whatever your heart desires as far as thickness goes.
Does anyone know if the H&Rs are lighter than the Kics spacers?