CH312:
You cannot own a full auto firearm in Canada (unless you were grandfathered in, so that won't be you at 18).
There are a great number of semi-auto versions of full auto guns available. If they are converted full autos I believe they are prohibited as well, but I think there are some that are restricted (must only be fired at gun clubs) only.
You may want to look in at
www.canadiangunnutz.com . there are a lot of guys there who are really into black rifles, and could advise you.
I know Marstar at
www.marstar.ca has Chinese made (Norinco) semi-auto versions of the M14 (their model M305) that costs only $399. You could then put out all the loons you want tricking it up to look cool. That should eat into your $14,500

.
Lever Arms has several AR type guns on their site at
www.leverarms.com (bushmaster, Norinco M311, AR 15) but I don't know what their status is as far as possession and use are concerned.
Rick