PhiPhiTheFlowerGirlI might decide to take spammyh's idea and go cheap. Which of these do you think will be best for me? I'm leaning towards the hp but idk.
If you live in australia all of these suggestions are worthless to you and in a different currency.
For $600 pretty much the only option you have to get a laptop that runs tf2 decently is at the dell outlet site that they use to sell computers that have been refurbished/returned for some reason, at a discount:
http://www.dell.com/learn/au/en/audhs1/campaigns/dell-outlet-au
I personally got an Inspiron (i5-4510u cpu and 840m gpu) from there early last year for $599 from memory, and it runs tf2 at around 100 fps.
Unfortunately they don't have any stock at the moment (because the deals are so good when they do appear that they get snapped up quickly) but if you check it fairly often you might find one at some point.
Otherwise you're not going to have a great time with getting a laptop that can game for much less than $800-900 without buying one second hand. And you can't really build laptops yourself, that only works with desktops these days.
I also recommend comparing the passmark scores of the cpu & gpu of any laptop you're considering to the scores of my laptop's parts to allow you to estimate the fps you might get. Passmark isn't that representative of gaming performance, but it's a good guideline.
my laptop's CPU (you care about single threaded performance for tf2, and don't buy anything that doesn't have at least two cores)
my GPU.
If you can get a GPU with a score of around ~700 or above and a reasonably similar cpu to mine, with a single threaded rating of ~1500 or so, with at least 4gbs of ram, you'll be able to play tf2 at a reasonable framerate w/ configs and high performance mode on etcetera.
holofernesi had an ideapad y510p, probably just within your budget. it ran tf2 comfortably at 60hz.
still, i would not recommend getting a laptop unless you have to carry one around with you.
This looks a bit out of his price range tbh