Webers like 3 PSI, so I'm surprised you got away with no fuel pump, but if it worked for you... I ran 2 40DCOE's on my Europa in the 80's.
I say a grand to tune it somewhat sarcastically. It would have to be done at a shop that really knew what they were doing with that carb, on a Harley, and with ALL the pieces that can be swapped out. Then it shouldn't be that bad. But, not having those pieces in place will make it much more expensive to tune. Like, what size chokes to use? Guess wrong and if you have to buy more, there goes the budget.
DellOrto parts are getting kinda rough to source right now over here. There's some places, but not many. I have a pair of 40DHLA's on the shelf.