Dbphd, I suppose the only real answer to your question is that the moder has cheaper labor and may be more able to ignore the parts cost as he or she is not working through a dealer network. Price point concerns are the only real difference.
Esoteric Mods
I own an Esoteric P70/D70 Transport and DAC, I am considering having both modded. I have been doing some limited research, however I would like to hear from anyone who has had their Esoteric units modded to get some feedback. My units are still under warranty for another 6 months. I would like to know the names and websites of some reputable companies I can contact. Bottom line is it worth investing into. Thanks for your help