I happened to get an epic deal on my Epiq. No pun intended. I paid $2100 for a 2 year old 60. Didn't even realize it was an Epiq until I got there to look at it, but when I did, I didn't negotiate, I just paid the man the money and left. Now that I have it, here are some thoughts:
This thing just "feels" good. If anyone else here is a Peter Egan fan, he described the feeling you get when you first open a drawer to find all of your tools laid out nice and neat when you are getting ready to turn the first wrench on a restoration project. That is kind of how I feel almost every time I open the drawer. Like a nice mechanical watch. Or getting into a nice German luxury sedan. There is a tactile feel to it that is analogous to a luxury item (I'd say a hand made suit, but I wouldn't know!). A filet mignon has the same nutritional value as a hamburger......but tastes a lot better!
I'm not a technician, I'm a DIY-er. But a pretty ********* one. My business shares space with a race shop (owned by my business partner) and an off-road shop (friends, but not business partners). One guy keeps his tools organized, the other guy does not. The guy who does has a big honkin' Epiq, kind of like the OP's with the cabinet on the end. When I have one of my race cars in the shop, or am helping out with one of the race cars, it will take me probably twice as long to do a job if I'm using the unorganized tools as it does when I'm using hte organized tools. WHen I'm at home, the little free time I have is valuable to the point where it is worth the cost to have adequate tool storage for me to pay a premium.
That said, I have some Craftsman toolboxes. My old ones, which I now keep at a lakehouse we own, where I need some tools, but not as many. I will say this, I would never consider going back to a cheap box as my primary box, ever again.
So all that said, how much I would pay would depend on what was driving the question. I would absolutely pay a big premium for the Epiq over say a 1022. New they are what, about 25% more? I'd pay 50% more in a heartbeat. Probably 75% more. A similar Master series would have to be under $2500 if I could get an Epiq for $4000. So the better feel to it is worth that kind of premium to me. Again, that is just the feel. And I'm sure folks think I'm crazy, but honestly, when something feels that good, it gets taken care of better. I'm just more inclined to keep things straight and clean in there. It makes doing a job I otherwise dread almost enjoyable. I'm sure the pros don't feel that way, but as a DIYer, I absolutely do
Now if I needed more storage space, it would drive up how much I'd pay more. Again, that gets back to how valuable my time is. If I truly needed to do something for more space, then I'd probably pay more.
So if I were to go back, I guess I'd say that if I had no box, I'd probably pay $5000 for it, so yeah I'd jump at $3700. If I were to have a chance to replace the Craftsman box at my lakehouse, I'd have to get another crazy deal. I'm not sure where you'd fit with your second box. If this second one you are after is like replacing my Craftsman would be to me, wouldn't pay the $3700. Maybe $2500, but again, that's because I don't need it at all.