You just edited your post that said you could fly for $50, now it looks like you are correcting me. :-/
You seem very optimistic, but think it is rather unlikely that you will end up going at this point. Try actually getting permission from your parents.
And portables are actually a terrible way to make money.
The odds of you making and selling 3 N64 portable between now and then is pretty low, even the fastest people like SS do not work THAT fast.
Here is what it will cost you:
Required:
$300+300+$15 checked bag fee=$615
Comicon tickets (including tax): $20+$20=$40
Food: Count on $15 per day, per person. $60 (Assuming you get there, go, and go back the next day)
Hotel: People who are staying all 4 days pay less, but for your share, it would be $15 or 20 per person, so $40.
Optional:
Rental car: $60, if you get a decent deal
Money for stuff at ComiCon: $50?
Basically, you are looking at a bare minimum of $750 dollars, and it could go as high as $800-900. A lot of people are getting a ride with Beta, but you are pretty far out of the way on that trip. Plus, I think the car is full.
Get permission from your parents, then make a portable, I will put you on the list. Until then, it is not realistic to expect you will manage to go.