Renderotica

First the legal ramifications are a hot topic. You would have to provide their consent, in a form that they be providing it with detailed allowance of this form of content being ok to recreate, not from yourself either like here is their consent letter. 

For the amount of work involved, $50 is way too low of a price to hand craft a character morph, texture the model, and go through the motions of animating the movie. Plus time involved for rendering out the animation which is hours sometimes days for just a minute or so of animation. 50 is way too low for all the work involved, especially if the person can't make a turn about on their work in the marketplace. Depending quality and length of video, your looking at $500 off the start maybe more.

Chaosophia Store link

This thing again...?  Years back there was this site called "Elfwood" and one person sent out 1000 emails requesting a D&D character...  Really neat meme coz so many non-pro artists eager to please.  Luckily it's still slightly difficult (compared to Damn hard) to make a human figure or customize a character so people think first...

Well the more established pros have spoken and I agree $50 is way too low.  It'd be $200-$300 for it to be worth someone's time...  Minimum... 

My advice - BUY  Poser software...  Well there's DAZ but I don't support that.

Also get some image edit software - Gimp and Krita are free.  For something like the "Shop" industry standard but cheap one time fee Affinity.

Get Poser - you can do trial - consider some morphs.  Look up the finger tool for custom morphs.  A few newbie tutorials.  V4/M4 on Daz are the industry standards now.  But if cheap you could probably use Poser base figures...

Then - your private use only - plenty of legal issues even if you 'share' it for 'free'

Once you get through so you can load the figures, render the figures, pose them, etc. THEN - use the "Materials" room to find the textures.  It's easy enough to get photos of your ..."Friend" to make an image map to stretch/shrink to the proportions.  The "Face Room" is designed to help with it but I've never used it.  Generally if you can match a map by copying the first map, saving it as a seperate file, over that layer fitting your images - well it works great.  Most of us here have used it to change skin color, add tattoos, etc.

Finally there's the bone structure which if morphs don't cut it work out custom morphs with the finger tool.  Free and cheap tutorials on that alone.  I use it a lot.  No, not helping, just telling you its there.

That way for buying Poser (or going with 'free' Daz) you have a workshop and can use a bunch of free props for basic room, furniture, etc.  Have your "Friend" doing whatever you want.

Oh, and if you post it here - please do NOT say you were the guy/gal doing these posts or this "Custom DIY character" is based on a real person.  The Admins would freak out - and in that case I'd 100% agree with them.  Reveal it, they'd likely take you down unless you mailed them a signed copy of an "Official Model's release form" - snail mail - otherwise your "Friend" could decide to talk to a lawyer and get several million $ as crazy as CopyWRONG is, though the politicians that excreted such laws had good intentions at the time...

Sounds complex but the time you'd spend to work to get the more likely $600+ to get anyone halfway capapble to do it, you could learn the software and do it yourself and have infinite private use of a good image of your "Friend"...  And this advice is only for your own personal enjoyment, we've said many times the legal issues to warn you and wash our hands of it.

And - btw - I almost did this -not for a "Friend" but wanted to make a statement about the latest "Star Wars" movies.  Wanted to feed the main characters, textures pulled from photos, namely the "Jedi" and that purple haired "Diversity Hire" ...General.... to the Saarlac...  But too busy with real projects trying to make $, same reasons as above Admins would freak out and rightly so and finally...  that'd be cruel and horrible treatment...to even a fictional Saarlac!

I wonder if anyone's tried using deepfake to do this. I mean doing the animation in DS/Poser, then using deepfake to paste their "girlfriend"s face on the model. The only problem is it needs a bunch of frames (like 300+ I think) to calibrate, but it should be possible. And it would be a lot easier than making a custom face morph/texture.

The $50 fee is laughable, but so is the legal worries behind making a poser head and getting sued for a million dollars. If we are being realistic all around, an artist should be paid half before dedicating all the time into the job. Its become a freelance norm