@ossobuco,
Okay, Osso, I can see 'bored'.
This is the fallacy of grammar teaching. Some think that by teaching grammar, which largely means memorizing inflections [or more often failing to memorize] or other useless bits of information, you teach people about how to use language in a better fashion; you teach them how to speak and write better.
MJ's information is useless, no slight on him intended, for trying to determine why 'were' was chosen in the original example.
Let me now say that I don't think the situation described in that example, ... better bring it forward,
When I was his age, I 'd have liked the cash (if there were enough OF it),
is an example that needs the subjunctive. Joe Nation also feels there is something "wrong", ... maybe "strange" is a better word [it's less loaded].
Here's why I don't think it's a situation that calls for the subjunctive;
*When I was his age, I 'd have liked the cash (when there were enough OF it)*,
[*....* denotes ungrammatical, or in this case,
denotes what I believe to be an ungrammatical sentence.
Let's make one more change;
When I was his age, I 'd have liked the cash (when there was enough OF it),
Now, I believe we have a grammatical sentence.
I think that what the speaker was saying, [note, I'm saying "think"], can be summed up with this paraphrase,
When I was his age, I 'd have liked the cash (if/when there was enough OF it given to me),