Best Buy is a chain of electronics and consumer durables stores.
I'm not primarily concerned that he's not earning enough money, though I have pointed out that most American males end up supporting wives, ex-wives, children, etc., and that his current paycheck won't cover such things.
My main concern is that he is obviously not enjoying life. Are my (and my wife's) expressions of concern and support making him more depressed, or are they helping him find a way forward? Clearly, children can continue to worry their parents even after they are technically adults!
I think he's sensible not getting mixed up with women if it's going to get so expensive; or that he meets one who has an independent income. He just might not want to get married or even have a girlfriend, and these days, quite a few people never marry.
The rat race and the white picket fence and 2.2 kids is not for all of us and it would be a boring world indeed if everybody were the very same.
Is there a hobby he could take up where he might meet some like-minded people, or even an adult aspie support group in the area?
Is he actually saying he is unhappy/feeling in a rut etc.? Some of us are told quite constantly to "cheer up" because we rarely smile but just because we don't smile doesn't mean we are depressed. I can't speak for your son as I don't know him but this is a point to consider.
Anything that could be construed by your son as pressure to "get a better job", "get a girlfriend" etc. is likely to be counterproductive, making your son dig his heels in further and be totally averse to considering any change to his current behaviours.
It often takes us years later than most to work out what we want out of life and then to decide how to get there. I'm in my 40's and still have far to go.