I purchased a use Sony SACD 9000es with Vacuum State Level 4 upgrades, and had them bring it up to Level 6 for a minimal charge. All told, including the used purchase price ($400) and the price paid for the mods ($1800), probably around $2200 has been spent on this player, and it is probably worth around $1200 on the used market.
I haven't found a stock player at even $2000 used that can touch this unit. I am going to bring home an ARC CD7 to compare it to one of these days, just to see how it stacks up. The stock SCD-1 wasn't even close to the Level 6 9000es. I expect the CD7 to beat it, but how much better it is will be interesting.
If you figure the mod is well-thought out (most of the modders listed in this thread have done hundreds or thousands of CDP upgrades and all have been well reviewed), and perhaps you paid $1500 for that mod; you would be quickly looking at a $4500 upgrade if sold at retail. In addition to the cost of the player, you can get into some rarefied air pretty quickly without spending a bunch of money.
I have a feeling that when I upgrade, I will be purchasing another "already upgraded" unit, probably Modwright Platinum truth, Wadia with GNSC mods, or an SCD-1 with VSE upgrades. Those units in the $3K range used probably are as good as most anything on the market.
Any idea why modded players aren't more popular? They seem to offer, by far, the most bang for the buck.