Jonel,
200 QAR for each Family Visit visa. You submit the documents, if they accept it, you will be notified about Visa issuance & then you have to pay and print the visa. Documents needed are as below:

1- Sponsors NOC in Arabic. Ask your sponsor to put in your family details such as Name and PP no.s of your family members to be visiting. It really helps.
2- Get your marriage certificate attested by Qatari Embassy in your country.
3- Get the no.2 document translated in Arabic from a certified translator here in Qatar.
4- Take these documents to MOFA (Ministry of External Affairs) or Baladiya and get MOFA stamps. If you will go to Baladiya they will charge you 20 QAR for each document.
5- You must also get your degree certificate translated in Arabic and get MOFA stamp on it.
6- wife's and your pp copies
7- Your QID
8- Your residence contract copy in Arabic and stamped by your Residence owner
9- Your work contract copy
10- Go to any typing center and get the application form typed. Take your wife's pp with you for that.
11- Keep 6 months bank statement as a backup just in case if they asked.
12- Your sponsors computer card copy