i wouldnt recommend anything less than a gtx 750, as long as you have a pci-e 2 slot your good to go as it doesnt need any supplementary power from the psu.
you can pick 1 up for about 80 notes.
anything less is just wasting your money. yes cheaper cards may well play it but it wont be smooth or consistent fps. the card is strong enough to give 60 fps minimum on low-medium settings.
What would be any laptop under 100 dollars that will run Halo: Combat Evolved?
Well the problem is that windows alone costs about $100 and the game only runs on Windows. Since these are older games we are talking about, I'd recommend you to get an used Windows XP laptop (older games are usually made for XP).