The primary advantage of the certification is to help you get your foot in the door. But you indicate that you already have 6 years SAP SD functional experience, so you have at least more than a foot in the door. If your six includes considerable configuration and a strong understanding of the SD module and it interface points, you should consider these options. Walking in and paying for the certification exam only. Take the test get the certificate and save the money required for the course. Seek a full time position with a company and negotiate for them to pay for the course and the exam fee. With six years experience you should be a safe bet to pass, immediately generate billable income. You should really look at the certification as a means to more responsibility and leadership on projects which should include greater pay. If you don’t want those responsibilities then their should be no reason to get certified in SD. Continue as you are. Or another option which I think is the best, consider a functionality that is more in demand, with SD experience, SCM, or APO might be a better course. Again try and get an employer to pay for training, or try study it yourself while on other implementations and walk in for he exam. Those certifications are definitely better than just SD certification.