Hey Kevziek...I know what you're saying, but many of us buy our components because we like to listen to music through them. We're not all buying them as future investments. Why buy something if you assume you're going to be selling it in the future? Isn't that some indication that you may be buying the wrong piece?
As far as Mike Elliot's upgrades go...he is pricier than someone like Stan Warren, but he also has a very different business. He's not tweaking other people's inexpensive products to make make them perform better...he's tweaking and rebuilding his own medium priced / expensive products to improve on his own original designs. He has a ratio of 50% parts to 50% labor charge, and he doesn't keep that a secret. His $2,000 upgrade has $1000 worth of parts. A $10,000 preamp may also have a $1000 worth of parts, and may not sound any better. I bet that they'd sound much closer than you think.
Let's assume you're right, and there really is absolutely no resale value for modified equipment. You spend $375 on a preamp, and spend $2000 upgrading it...only to sell it for $375 two years later. If you purchase a somewhat used $10,000 preamp for $6,000, and sell it for $4000 two years later you're still losing $2000 in two years time. The only difference is that with the more expensive amp your putting out $6000 instead of $2375. Buy the used Counterpoint...spend $2000 on upgrades...invest the extra $3625 into mutual funds, and after two years time you will have $761.25 more than you would if you purchased the more expensive preamp (figuring an annual return of 10%). Although the more expensive preamp will have much nicer knobs and look a lot more like a UFO, for what that's worth. The only bad thing about the Counterpoint rebuilds is that you can't go out and listen to them ahead of time, but everyone that enjoyed the sound of Mike's original designs really enjoys his rebuilds.
And to answer Jacks@aol.com...his preamp upgrades do involve a lot of parts swapping, bypassing some extra circuitry, improving the output path, improving the volume control, upgrading connectors, etc. His amplifier rebuilds are partial to complete rebuilds (depending on the cost) that are based on Mike's new designs. I am currently having my SA100 amplifier rebuilt, and the only original part that will be kept will be the chassis. He gives all of the details at: www.altavistaausio.com His Counterpoint rebuilds are actually similar to his new line of Aria amps. They're not out yet, but they look very nice (you can link to them thru his site). He's even offering lifetime warranties. That's pretty decent, if you axe me.