MB,Does the $90 include powersupply? If so, that's a great deal.
Marchand's prices aren't pricey. I just looked at ESP's pricing for boards and they're in the same ballpark ($20-$30). What I can say is that Marchand's boards are very high quality. Thick and rigid, double-side and teflon coated. The brackets and heatsinks you can order with his amp boards are drilled and tapped to fit the boards perfectly.
Marchand's version of the GC (PM21) is available as a stereo board for just $20. $100 gets you all the parts and the board. Sounds a bit pricey, but the design gives you the flexibility to run the amp with inverting, non-inverting, or differential inputs after it's been assembled. You can also get a power supply unit that includes a 160VA toriodal with 20,000uF per rail for another $100.
I know this sounds like a commerical for Phil, but I think his stuff has been overlooked and underrated.
g.