Planning to get a cheap-ish GPU. Would appreciate some advice.

Hi, I've been wanting to run my own local LLM for some time and I finally saved enough to get a budget GPU. I can spend 700$ at most, and I'm looking for a GPU that can run quantized 30B~ parameter models with decent speed. Being able to run Qwen 3.8 27 B Q4_K_M and similar models at +20 T/s is good enough for me.

I mostly looked at Chinese shopping platforms such as Taobao and Alibaba since I've read here that they had cheaper listings and I found these prices:

Modified RTX 3080 20 GB for 570$

AMD Mi 50 32GB for 390$

Modified 2080 Ti 22 GB for 330$

These are all from sellers with 10+ sales, so they're probably trustworthy. Any cheaper selling prices I found are from accounts with 0 trading history and look like scams.

I'm planning to buy a modified 2080 Ti 22 GB, which, with customs, shipping, and other expenses, adds up to around 530$. Do you think this is a bad deal overall? Should I instead go for an AMD Mi50 with 32 GB? Because the model will have a really small context window with only 22 GB. Should I just go for two Mi50 16 GB for 240$ total? I even found a seller with a high number of sales who sold Mi50 32 GBs for 230$ but they were selling in bulk, so I needed to buy at least 5 of them, which is unfeasible for me.

Sorry for the long post. I didn't expect it to be so hard to find a good deal, and I don't live in the US or the EU, so I can't look for local or Facebook Marketplace deals. I would really appreciate some advice.