Hi Mesut- there are no bundling deals available on the cost of exams. If you are a student, you may be eligible for a discount, please check this page for further information:
https://docs.microsoft.com/en-us/learn/certifications/student-discountsOther than that, Cloud Skills Challenges sometimes come with a reward of a discount or free offer for certain exams; keep an eye out for these by following Microsoft Learn on twitter or LinkedIn.
For instance- you can complete this one for 50% off the cost of one certification exam (please see the terms and conditions at the bottom of the page):
https://developer.microsoft.com/en-us/offers/30-days-to-learn-it
