Magic Price has been an issue since Methuselah was in diapers... one dealer would want just a single 12 inch long fish while others wanted two or three for the same set of cups and four matching rocks...
The "cost" of magic has to be looked at in a couple of ways, the first being how unique and/or rare an effect really is. Then you have name recognition when it comes to the person that created it as well as who they have been lucky enough to have endorse it. Then comes that other evil -- DEMAND! Not just the fact that people want it, but who wants it and why.
If you have a half-dozen big names clamoring over a piece and offering you big $$$ for exclusivity then you know five or six years down the road when you actually do go commercial that you can ask a hefty penny for it. On the side side of this coin, if you just approach Murphy's out of the gate they are going to compare it and much of what I've stated already and come up with what they think the market will bear.
I have an item that I've invested several years compiling and pulling my hair out over that has a retail list of $245.00... that price is about $60.00 less than similar manuals dealing with the same general topic but it is likewise priced so that whoever buys it will have more of an exclusive to the information vs. what would happen if I dropped the price by a $100.00 or so and made it more affordable. The price accomplishes a sense of exclusivity and too, those that make that big an investment are more prone to actually USE THE INFORMATION rather than let the book collect dust on a shelf as so many books and tricks ultimately do.
I've touched on a few of the factors that affect price but I've not pointed out time and material. A great example of this is the Swami Spirit Altar made by Dan Blaine of Lebanon Circle which retails for about $1,250.00 U.S. That's a hefty chunk of change for one effect but when you actually touch one you will see why it should be twice that amount.
The primary device that makes the thing work has a retail value exceeding $300.00 by itself, the craftsmanship and detail that went into the piece is on par with what I've seen come from major builders like John Gaughan, Bill Smith or Owens -- it's top of the line all the way and easily 40+ hours of personal time for each unit. When all is said and done Dan is making just slightly over minimum wage for his time and talent... not exactly what you'd expect to hear when it comes to a device "costing" that much but "cost" is much different that "value" and as I said, the value of this piece, like other pieces Dan has shared with the world, is far more than what he's asking.
My point (I hope I'm not confusing folks) is that Dan could legitimately charge much more but he knows he's a "new name" and until he can break over a certain threshold he's keeping his prices more than fair for what you get. This is a philosophy being followed by a few others like Bev Moore and Elliot Bresler.
There are other "cost" encountered by the seller of a piece depending on the route of course they plan to take; you have to send out about two doze to three dozen copies of your piece to key reviewers as well as key personalities in order to get feedback. That takes time as well as money and even when I was working with Creative Illusions and we had a new piece to share with our VIP client list we were looking at a mailing cost of about $50.00 per customer out of pocket and then, when you find something that clicks you have that $500.00+ per publication ad cost (average). That's why a piece like Shadow Vision that cost us right at $5,000.00 in materials and man-hours each to build retails for $15,000.00 with road cases (an additional $3,000.00 +), etc. After all we also had the shop and warehouse overhead to deal with and a ton of other expenses.
I know I've jumped around a bit but the question applies to several different scenarios and I'm trying to give you the best possible picture as to what, how and why from each perspective. Hope I've helped
