Did you get hub and wheel centric ($300 for 4 ouch)
they look high quality, but $200 for spacers is kinda pricey I think.
I still have to wonder how important is hubcentric if it's just a spacer (not an adapter) afterall the wheel's position is not changing, it's just going to sit out a little further.
$50 for a set of these:
Speedwaymotors nonHubcentric generic wheel spacers