Here we go again... Custom heads, depending on who did them can cost you a fortune. Single head sculpt (HS) by a reputable head sculptor (HSr) can cost you thousands of dollars for one single head. A non-reputable HSr...maybe a hundred or so. Usually the price that you pay is what you get. More money, the more it looks like the HS you wanted, the less, more like the HS you did not want, but will take.
There are 3D artist that can do the head, again, reputable and non-reputable here applies. Most HSr use 3D process.
Here is a 3D artist that the price is not that bad:
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