Missing models and textures?

Hey, this is my first post on Facepunch, here it goes:

I don’t know my system specs, but I know I can run Gmod just fine, its not a hardware problem. My problem is, I have purple and black on MOST textures, and errors on most maps that I download (Like Gooniverse). I bought Gmod with Team Fortress 2, so I guess that doesn’t come with the right textures? I already have PHX mod. Anyway, I want to get that working, so would I have the textures if I got Half Life 2: Episode One? Because its only 10$ right now, compared to Half Life 2’s 20$.

P.S. I read the stickys and such, they all pointed me here, so I’m pretty sure this is the right forum…

P.S.S. Sorry about the lack of system specs, but I don’t know them, and I’m pretty sure you guys don’t need them.

Thanks in advance.

EDIT: I just read that CSS is mostly used for these. Would I have to get that too?!?

List some of the maps… other than gooniverse?

EDIT: Most of the gmod maps do need CS:S So that could be the problem…

Just buy CS:S, its really the only game you need with Gmod, getting the orange box too makes it literelly error free from texture problems.

You should have bought Gmod with CS:S not TF2, TF2 is a great game of course but if you only wanted to play GMod it would have been better.

Ugh! That is uncool…
I don’t want to pay for more stuff…