You can buy a VW style or Passat firewall mount dual reservoir for $13-$25 and add inlets to a stock MC lid. Beats $110 plus ship.
I like your style,I had a VW Bug one in mind, it would beat the heck out of the rigmarole of topping up when bleeding brakes etc.
I just haven't got round to it yet.....
The only issue I haven't addressed is on my M/C,the gasket is a one piece affair that covers the whole of the top of the reservoir,i'm not sure if it would be OK to open it up to allow fluid entry from the cover.