The spectrum does not affect the longevity of the lamp, so no worries there.
If you are not using actinics, then I'd choose 14K lamps. You can always add actinics a year from now during your 1st lamp change, and change to 10-12K halides and add actinics.
One thing you may try is talking to some commercial electricians in your area. Many office buildings are "suites" that are pre-finished half warehouse, half offices. Lots of times tenants move in and build out the warehouses as offices (it happens ALL the time). The electricians come in and tear out the halide fixtures in the warehouse, and usually they take them with them. I wouldn't be a bit surprised if you can find someone who will sell you a couple of 400w fixtures for $20 or maybe even give you a couple if you play on their sympathies as the poor 16 year old with no money...
A 400w fixture will yield you a ballast, mogul socket, etc, and will run any American made SE 400w halide lamp (Hamilton, XM to name a couple).
Just make sure if you try this to ask for either 120 volt or "multi tap" fixtures. Multi Tap fixtures can run on 120, 208, 240 or 277 volt. Lots of times the fixtures are 277 volt only, which won't run off either 120 or 240v found in homes.
