Eh, about getting bikes stolen: now I feel I need to tell my story. And with this story, I guess you could identify who I am if you wanted.
I locked up my old Santa Cruz Blur (not the Blur XC) in Harvard Yard, right in front of my House (Dudley House) and went on a date. Came back, and my bike was stolen. It was one of the saddest days of my life. Not because it was a monetary loss, but because someone had the nerve to take something that was not theirs. When the Harvard Police came, they asked if I had any type of insurance, after learning the value of the bike. I said "renter's insurance". They told me to contact them, so I did. It was a nice surprise to learn that even though the theft did not happen in my house, it was covered because the property is from my house. Two weeks later, I got a nice check for $3800 to build a new Santa Cruz Blur XC.
Moral of the story, I guess, is make sure you get renter's insurance when you go to college. Deductibles can be $100, it's very cheap, it covers dorm rooms, and it's worth it. It may not replace your bike since you're looking to spend $200 (but keep your receipt anyway), however, sh*t happens. Add up the value of your clothes and I bet you'll be astonished. Add up the value of all your electronics, etc.. Ask your parents to bundle it on with all their other insurances, but don't neglect doing your own searches on the Internet.
A few comments from the above posters: no such thing as tubes that don't go flat. You can get downhill tubes put in most tires, but they still go flat. And don't even get me started with UST tubeless systems.
If you have a budget of 1,500, it's going to be tough to build a good, custom bike for that much, even going through mail order shops. Honestly, I look around MTBR a lot, and find some screaming deals on mountain bikes. Typical markdown for a used top-of-the-line bike is over 40%. (That includes my Turner Spot, if anyone wants it for $3000, it's yours...

) Now if your budget is 4k+, THEN you could build a great custom bike.
I would argue disc brakes *are* needed. However, the OP simply can't afford them. Disc brakes pay in dividends once it starts raining. It rains in California, right?

So he'll have to make due with V-brakes, and will have to be extra careful when it rains (brake sooner. And while we're on the subject here's some knowledge for you: 70% of your braking power comes from your front wheel. The rest is your rear. That does not mean you only brake with your front. You should break evenly (and the bike shop *will* know, when they replace your brake pads if you were, so you better for goodness sake ;-)). And you brake slowly, building up pressure to stop. Do NOT lock your brakes unless in emergency. When going around corners with loose gravel/dirt, use your rear brake only to slow down, it will help guide you through the troublesome area).
Don't consider a BMX bike. You won't go as fast and lose too much energy.
I have a friend in Switzerland who got a 400 CHF (roughly $400 USD) fine for riding his bike on a one way street in the wrong direction while talking on his cell phone.