Holdontoyourhat,
No, he didn't likely want the money; he was more interested in trying to cover up a familial murder by using a fake ransom note.
But the young perp didn't have a clue in regard to an appropriate number to use as a ransom demand. From check stubs he knew that $118,000 had been paid to John Ramsey and he could have figured that was the total amount of John's pay for the year, IOW, a lot of money. If a very young male wrote the ransom note, to him it would likely have seemed like a very large amount of money, so he used it.
BlueCrab