Salesforce arrange some training seminars for half-a-day and issue certification vouchers with a discount of $140 from $200 certification fee. You can register and attend any available training at https://trailhead.salesforce.com/en/credentials/cert-days/ and apply the coupon for any exam that you take. Currently there now certification days events are. Keep wathing the link time to time.  Also, you can register for the same training and receive the coupon code. Note the the coupons issues have expiration dates too. I attended the seminars and made use of coupons thus issued.  They are very useful training at least to get the scope of your certification exam.  Good Luck