Why are you not applying for a visit visa from the Qatari Embassy? If you are just visiting then it should be straight forward.

Buying visas is illegal - the net person is a scam.

One of the reasons it is difficult for some nationalities to get visas of any kind is that their countrymen have abused them in the past (over stayed, worked illegally, etc.) so the Qataris want to be sure you are coming for legitimate reasons, won't over stay, won't do anything illegal and that you will leave at the end of your visit.