The application fee for SINP is 350 CAD, no more no less. If you get ITA, you can apply. What's your SINP score? Once you apply, you will wait for nomination? You don't get VISA right away. It's a long process. 1st Nomination, then ITA for PR application. The whole fee for PR application is 1,325 CAD for a person and may increase based on the number of family member.
So my request is do not give any one any money without proper document. Like an ITA letter from SINP, your account in OASIS. these are way to confirm validity. Plus, for paying the fees you must use your own card, nobody can pay your application fees using their cards. SINP is very clear about this.
Here are two links from SK government and CIC where you will find details of fees of SINP and IRCC:
https://www.cic.gc.ca/english/information/fees/fees.asp
https://www.saskatchewan.ca/residen...nal-skilled-worker-saskatchewan-express-entry