Pat:
THG's stuff is pricey, but the quality is there and Roger gives good customer service. He's done knobs for my Orion as well as my Heritage Golden Eagle and some really sharp cocobolo knobs inlayed with MOP for my Custom Straub Cantus guitar head. I'm currently in the process of getting Roger to make some custom knobs for my new Series I 4-str.
FWIW, if you get your stuff made before Alembic ships your guitar, Rog can ship direct to Alembic and Alembic will put the stuff on for you. This ensures perfect fit/finish and Alembic will note the option on your build (blue) sheet (aka wood card) for all posterity...great for insurance claims, should it ever be necessary.
Cheers,
Kevin