So many options
With the $1500 you're budgeting you can buy yourself a pretty nice bike. You'll get a killer hardtail for that kind of money, and if you shop wisely you can find a good deal on a full suspension rig if you're inclined to go that way. As for buying from the LBS as compared to online, if you're comfortable with the risks of buying sight unseen and without a test ride, Ibex is a great option. I own an Ibex, and furthermore, my full suspension rig was purchased from an online resource without me seeing or riding the bike first. Th risk is finding out that you don't like how the bike feels, as well as the logistics for any warranty service should you need it. The reward is that your dollar will go much further buying direct. Hopefully your parents will buy into the direct from manufacturer option. if not, i wouldn't rock the boat, even though you'll be 18 and should be able to make the decision yourself.
Let us know what you finally decide to purchase.
Bob