It's hard to do it all for free. Cheap I can help you, because you need the materials :)
I would say, because Neil Diamond is very attractive ... Go with a Ken Doll. Preferably one you think best suits Neil Diamond. You can either buy ken doll clothes on amazon or e-bay, or if you're feeling really ambitious you can make your own clothes and ken dolls." Knit Fashion Model Doll Clothes Knitting Patterns for Fashion Dolls - Vintage Doll Clothing Patterns to Knit" is a book on amazon that you can use. If you're going for the older Neil Diamond look, I would say buy a ken doll with plastic black hair, then get a Valspar all-purpose spray paint in Grey, you can even get a cheaper one. Cut thin pieces of masking tape, and put it on sections of the "hair" you want to stay black, then spray away, making sure you cover his face and body with a wash cloth, or rag! You should get a salt and pepper look! You can even buy a few oil based paints to fill in his eyebrows, or even some magic markers, or some grey permanent ones. A guitar on e-bay for $12.00 here's the link, if it won't open type in google mini guitars. They have some for cheap. If you want his original black guitar I would say oil paint that as well, so it gets a nice shine.
Attention: NOTHING on this site may be reproduced in any fashion whatsoever without explicit consent (in writing) of the owner of said material, unless otherwise stated on the page where the content originated. Search engines are free to index and cache our content. Users who post their account names or personal information in their questions have no expectation of privacy beyond that point for anything they disclose. Questions are otherwise considered anonymous to the general public.