IMO, it depends on your perspective. I know you were comparing "custom" to "off the shelf", but I think the idea was basically "is a $1,000 bow worth twice as much as a $500 bow, will it shoot better", etc. etc. etc.
Of course it depends on the monkey holding the bow. We all know archery is a very mental sport, and I can think of at least one fellow I've shot with that seemed to be hung up on brand names/cost. I believe that if you gave him a broom handle strung up with baling twine, but could convince him it was a "big" name (expensive), he could shoot the lights out with it; but if you gave him the smoothest, sweetest, fastest, most forgiving bow ever built but he was convinced it was a no-name built in some guys garage, he couldn't hit a barn from the inside with it--and he is a dang good shot.
If you want fancy, rare, super exotic materials, then sure you are going to pay more--for looks. Paying a lot more won't mean a thing if the bow doesn't fit. One of the best shots I know has shot his best with an old Bear he either got for free, or paid no more than $25 for (I can't remember--it's been a while). Ugliest bow I've ever seen, but he could sure shoot it.
Personally, I figured out some time ago the price and/or the name won't make a bow shoot, and it won't always mean better (or even good) quality. I've shot "cheap" bows that I liked, and very expensive bows that I hated (and vice-versa). I like a pretty bow, but priority is a bow that fits and works for me. Price has practically nothing to do with that.
There's still a few bowyers that offer some very nice, high-quality custom jobs in the same price range (and less) than several off-the-shelf models--they will even draw attention for the looks, although probably not impress anyone with the name on them. I rather impress someone with my shooting than with the looks of/the name on my bow.
Just to clarify, I have shot some expensive bows that I really liked.....but for me, they were no better (looks, quality, performance, warranty, etc.) than some I liked at half the cost.
'Course I've owned some high-dollar bows, and will probably own another one or three sooner or later....but I have no illusions that paying more will make me a better shot.......
Chad