I would try your local dive shop first. Remember, cheaper is not always better. You are talking about "life support" systems that NEED to be there for you when you NEED them like at 60+ feet. The reason I refer you to a local dive shop is because of service. You can most of the time, depending on the shop, buy used or rental equipment and they will stand behind and service it. It may be hard to contact your ebay seller for a replacement part should some defect arise? If you don’t have a good local dive shop, I have done business and recommend Scuba.com, and scubatoys.com on the internet. Good equipment should last you a long, long time as long as you keep it serviced and in good order. Good luck and good diving!