Try to wait a few weeks for Black Friday as there were killer deals last year.
That may not happen as much this year as laptop usage is up due to Covid.
But there should still be some decent things on offer (if you can time it right).
But what should you buy? Try to aim for nothing less than an Acer Predator Triton 500 type spec: Higher end I7 - 16GB ram minimum (32GB preferred) - GTX 2070 / 2080 or equivalent hardware. 1TB SSD minimum (unless you’re planning to carry an external hard drive around - which is good for backups anyway). The thing about game dev when you need mobility is - its especially hard to get right with just one rig. I’ve come up with strategies over time, but you’re always fighting over-heating and therefore a shorter lifespan on the laptop. Capping max FPS and turning off real-time updates in the editors helps, but you still need to test your work.
So basically if you need mobility more than having a working screen, opt for a VR rig. Think HP Omen-X or similar. Super portable, yet cooling isn’t far off a desktop due to having vents on all major sides. The other option if you’re just learning, is go super cheap and just accept the limitations. See here. That cost a 10th of a production laptop, and yet its great for experimental projects / learning, plus risk of theft or damage on the road isn’t such an issue. But you have to run UE: 4.18 (so no ray tracing). But the positive side of that is, its actually far more stable, which is also better when you’re starting out, as you lose less time. Good luck!