There's a lot of talk about large models atm, but when you're learning you should probably stick to smaller models because the training time drastically reduces how fast you can iterate, and most jobs aren't NLP based anyway.
Remember also that 99% of problems classical models are faster and just as good or even better than neural nets. Of course if you're interested in neural nets as a hobby, go for it, they're truly fascinating and you can do some amazing things just in Colab, but they still aren't the best option for most real world problems.
After that, use a managed service with GPUs. They will keep all of the hardware working, you just pay a monthly fee. I have no interest in diverting mental energy from learning ML to how to build a computer so that’s what I do. I use Paperspace but it has some very annoying issues so I can’t fully endorse it.
https://coral.ai/
Or, search nvidia ai starter kitI also recommend at least 64 GB of RAM, and at least 2 TB of storage. It seems like overkill at first but man do the GBs disappear like magic.