I think Alfaholics and the broader restomod craze (see also Singer on the Porsche side) has changed that. But only the "big name" restomods get the big bucks. Homebuilt examples tend not to fetch those prices (even if well done and built with high quality parts) I think the fact that the motor was actually built by Alfaholics helps.So much for "only factory original gets the big money..."
Keep in mind that the GTA-R waiting list is approaching 10 years long and you are going to spend close to $500k in the end. While this car didn't quite get the full GTA-R treatment, it does serve to reason that an Alfaholics built car you can drive home today would get into the six figures.