FGJ- It's just time, money and opportunity, my friend.
Any "difficulty" encountered is in being vigilant and patient enough to catch these when they do appear. It's also a no-brainer that being part of the HFC helps considerably, as 5 of those 6 Cali's came from members hereon. The custom checked Cali was ordered thru, and with the help of a long-standing member (bcrgreg) and a lot of the mods on the others were effected by uber-talented folks on the board- bcrgreg, Murkat, and Stike.
On the issue of modding- I had someone "call me" on the actual meaning of modding. In his opinion, modding entailed making significant changes to the form or function of the guitar to the extent that it would be difficult or impossible to reverse the changes. I think there are degrees of modding but that's probably just semantics
In the end, value is how YOU define it. If a guitar is more valuable in a state/condition that is best suited to your playing style or aesthetic preferences, (as opposed to monetary value from an investment standpoint) then that becomes your defining standard. Modding a guitar to play/sound/look better according to your desires will enhance the value to you. In the end, as a guitar player, I find that to be more valuable than it's resale or "original" status.