Aaaachk! I feel soooo old!!!
*LOL* Geez, it's been 6 years since I lived with my parents... 
Only 2 since I haven't gone back for a few months, but
boy...15?  *moan*  hehehe...oh to be young.
I do remember how much living at home stank, but my folks
and I never really got along.  So I would think the best
solution for me would have been P.O. box, as long as it
was accessible.  I'd probably take the "what they don't 
know won't hurt them" attitude, but then I didn't ever
really have a desire to share my hobby with them.
The only one I have to contend with is my husband, but
he's pretty supportive.  I *still* don't tell him about 
the really expensive cels though.  ^_^  
I am pretty cheap though, most of the time, so I try not 
to spend that much- it bothers me to feel I'm getting 
ripped off especially if I know a cel is not worth what
the dealer is asking...so I do make myself poor, but it's
not as bad as it could be.  ;)
As a little thing to cheer ya up teens, at least 
you don't have to worry so much about not being able
to buy groceries cause you spent too much on cels, or
making car payment, rent...etc.  :)