So i've decided to make some more purchases on GoG, but i only have about $16 in my paypal account. The other day i bought Stronghold: Crusader and was very impressed by the site. I would like to buy a couple more games, though i'm split on what to maybe. Maybe you guys can help me.
The games I've been looking at are:
Fallout 1&2
Jagged Alliance 2
Sacrifice
Duke Nukem 3D
What would be the best combination for my money? Also, if anyone has any other suggestions, i'd be open to checking out more games.

Well you'll get few if any people suggesting you don't get fallout.
I've rather been enjoying Spellforce Platinum, lot of content for your money, good if you like rpgs & rts
If you're a fan of space sims, Freespace 1 & 2 are spectacular

You WILL get Fallouts, damn it, they'll swallow weeks of your miserable life! .. Promise. 1 and 2 is simply a must-have for any RPG fan. ... Promise.

I agree completely with that.
All 3 have been seriously modded, so you can download additional content from fan sites to further enhance gameplay, fun and lack of free time.
They're a must-have for none RPG fans too.
Fallout 1 & 2 were the first and so far have been the only RPGs I ever played and I really enjoyed them.
The moment you start playing you're hooked on them.

Ditto! Spellforce Platinum is fast becoming a favorite for me.
Same goes for the Freespace Series.

Yeah that cover art is amazing, one day I'll have to play the game...
Seriously though, its a damn good game with some pretty dodgy voice acting but as a whole its really good

LOL...
I must admit my visits to the bathroom have increased lately.

Any gamer worthy of the title needs to have played Sacrifice. And the Fallouts, of course.

I would suggest getting just one fallout game to start with, just in case you don't like it - it's not everyone's kettle of fish. I enjoyed Fallout 1 more, and it's a better idea to start with that for the sake of continuity.
I'd then suggest Duke Nukem 3D as the alternate, because sometimes you might get fed up with the strategy and just want to go kill things.

Fallout... $5.99 each, tis a must buy!

Fallout and Sacrifice. Then save up six more dollars for JA2 when (or if) you ever tire of those two.