Can anyone give me some additional info about this:
Men's Trek Alpha 4300 26" Mountain Bike w/ Aluminum Frame

It looks definitely worn, no doubts about it. But I can't seem to find that specific bike on bicyclebluebook.com.

2006 Trek 4300 - BikePedia

Bicycle Blue Book is pretty much crap. Entry level mountain bike, small frame, not a bad price but might need some work (chain looks pretty gross). If you fit it, maybe offer up 50 bucks. Hope you are really short though...

For roommate -

He's about 5'7" but yeah that chain and seat are needing to be replaced. We shall start at 50. Is that a good starting price or go lower?

PS: How the hell did you guess the frame size simply by looking at the pic?! I mean I can tell it looks small, overall, but that was awesome lol.

It says right on the seat tube, 15"/42 cm. Also, it looks small. Probably too small for someone 5'7", I would say this would be more appropriate for someone 5'2 or shorter -5'4 depending on the person

$50 is fine if it fits and doesn't need much work. The fork is likely at the end of its life.

I'd recommend looking for a bike without a suspension.

Nice catch! Totally did not see that when looking at the pics for frame size xD

He likes smaller bikes cause he used to BMX. But I personally agree with you but I am not the one spending the money

Picked it up for 40 bucks!

Frame is 16.5 so it fit him nicely. He likes it a lot. Will need new chain definitely tho.

Thanks all for the info!