Building a laser?

Hi, I wanted to ask some questions about lasers.
I'm pretty bored with school and want to work on a project for a while. I though of maybe trying to build a laser, mostly because it's really awesome, it sounds like a project that would be challenging but also teach me a lot, and it's sort of connected with what I'm learning now (EM). I just read some stuff online for the past half hour or so, and I found a site that seems pretty helpful: http://www.repairfaq.org/sam/lasercon.htm
I have no idea what type of laser to build (CO2, NeHe, Argon, etc.), mainly because I don't know much about lasers yet, so I don't know the differences. I'm very hard working, have decent resources (my grandfather and uncle both work at a good university, so I can probably get some stuff and guidance from there), and have a lot of free time. So, should I go for it?
Also:
Does anyone know of other sites (or maybe books) with info on lasers?
How long do you think it will take?
How much (approx) will it cost?

Thanks very much

PS. About a year ago, on one of my first posts, when I was more inexperienced and ignorant, I asked about building a particle accelerator. Looking back, I realize that it was pretty ridiculous- hopefully this post isn't a repeat of that :).