Most of AutoCAD is single-threaded. It does have a few multithreaded subprocesses here and there, but most of your actual waiting-on-the-computer time is going to be long single-threaded operations. That is in regards to the main GUI application, which you would probably be using most as a student. There is also a program installed with AutoCAD that can be found in its directory called accoreconsole.exe which is basically a commandline only version of AutoCAD that is multi-threaded.
That being said, it is sort of a moot point since you're not shelling out thousands for a workstation with many cores; leaving your options basically to an Intel Core i5 or i7. The difference between the i5 and i7 is that the i5 is cheaper and lacks hyperthreading, while the i7 is more expensive and features hyperthreading(which allows each core to run two separate threads simultaneously). If budget allows, I'd opt for the i7. At work, I tried running the i7's in our mobile workstations without hyperthreading for a while. It did not seem to make a big difference in AutoCAD's performance, but the performance hit while multi-tasking was noticeable, so it was better to run with hyperthreading.
The largest cost of those ($3000) mobile workstations was the NVidia Quadros that they had been ordered with. AFAIK, AutoCAD does not use any of the features that Quadros have that Geforces are lacking, so shelling out 5x as much for the Quadro is a waste for only working with AutoCAD. You may notice better performance with a Quadro while using Revit, 3DSMax, Maya, etc.
For a good deal, I would look for a laptop with an i7-4790k, as they are two generations old(cheap), and have single-core clock speeds on par with current generations. If you can find the 4790k in a laptop that also comes with an NVidia Geforce 1080, that would be perfect, but it will likely have a 980 at best given the generation. You will also need a good deal of memory, so shoot for the 4790k's maximum of 32GB. The last essential performance-related component would be your storage. I recommend getting two identical SSDs(256GBx2 or 512GBx2) and run them in RAID0. For peace of mind, you can pick up a third SSD and run in RAID5 so you have at least some sort of failsafe against a dead drive that contained your "big project". The last recommendation I have is get as big a screen as the remainder of your budget allows, screen space is very valuable in AutoCAD.
32GB of RAM and 3x SSDs would be leaning toward the mobile workstation sized laptops. The $3000 machines at work are a couple years old now, so they may be affordable now, especially used. They are the "HP Z-book 17". I personally don't recommend HP, as their business is mostly focused on selling service contracts to businesses, so there's likely something cheaper with equal stats from another manufacturer.
I am not familiar with what AMD has to offer for laptops, so I can't offer any credible alternatives to Intel/NVidia.
