Anybody have a problem buying modded units.

All "modded" units are not the same.
It depends:
On the unit.
On the reputation of the modifier.
On the mods that were done by that modifier.

My observations and IMHO, from having had 4 different modified pieces, is that money spent on the "right" mods (+ the original unit), gives you noticbly more improved performance, than the same combined amount of money spent on new/retail items.
Good Listening!

My Wadia and MFA amp sounds way better than stock,I think the only way to truly hear what a unit can do is to eliminate the safety issues (iec current limiting devices).With better i/c's and power cords one can hear how a component truly sounds,Steve at Great Nothern Sound Co. is a master tuner and has intimite knowledge of the unist he modds.He takes his time and actually listens to his work so that one doesn't get a quicky mod that doesn't feel or sound right.A good modd allows one to get better value before you get the upgrade bug,my MFA has had 16 year life and still has some original power tubes in it.After Steve's mod to the amp,I am still impressed with how it throws a huge soundstage with incredibles 3-d images and viceral dynamics.This amp competes very well in every catagory and I need to spend a small fortune to readily beat it.A mod is only as good as the modder,as Lkdog said " You need to do your homework " on what a modder has acomplished in the Agone community.Take care Dennis

I think modded units offer a huge bang for the buck and are tough to beat. Now, in saying that, I think you need to focus on those that have an excellent reputation for their mods, as well as their service and support. The modded units of these individuals are often very easy to sell.

I did not think of the resale value also, all I care
is to bring a good music to my room.
David if you want a taste of cd mod, I am willing to
bring my SonyModwright to your house and we can listen.
In this case you dont need to think about resale value.
I live close to you.There you can judge if my SonyMod
is worth the money I paid for the mod.

Just as an FYI, the "seller" may have not been able to describe the mod as some modders, like Steve at Great Northern Sound, do not divulge what components are part of the mod. Whereas, the Parts Connexion will email you an exact listing of all components that went into the mod.

I have had components modded by both of these companies (Resolution Audio and Sonic Frontiers) and sold the components on Audiogon within a week. I thought there was definite improvements in sound, and sold the items without losing hardly anything on the mods.

Like was stated in an earlier comment, it depends on who is doing the mod and what their expertise is in. For example, Chris Johnson with Parts Conn. once did R&D for Sonic Frontiers, so I felt more comfortable in utilizing his services on the SF preamp mod.