So, you're selling codes to a fishy site using an autobuy platform while all your reviews are given by newbie accounts with 0 trust and allmost 0 history.
What could possibly go wrong

In case somebody is missing the obvious sarcasm: you could get scammed at the autobuy platform, OR the OP could go for a double whammy and let you pay to receive an invite to a site that was setup to scam people...
There is no way a malicious user is going to sell you "dirty" BTC for 30-50% off, he'll just run it trough a couple mixers/coinjoins/exchange for XMR/hotwallets him/herself and only lose 5-10% instead.
For everybody reading this topic: if something looks to good to be true, it usually is... Don't get scammed...
Dude, this is your opinion, but you're right, of course, in many places everything is true, but my friend bought the code and he says that everything went great!