the cheapest mobo with DDR4 here is a z170, trust me, market on Brazil sucks, mainly electronics, we have half the things launched in USA by 4x the price
I have both, G502 is for my video editing PC and Death Adder for my Gaming PC. Both are great mouses. You can't go wrong with either. Razer software is more stable and bug free. Logitech still need to work out the issues out of their software (If software matters to you). If I had to make choice I think I would go with Logitech first. It's not to say Razer is bad, It still a great mouse. I personally like the removable weighs to make my mouse a bit more heavy.
I know some say if you have bigger hands you should go with Razer Adder over Logitech G502. I can't really weigh in on that.