Used gear is great as long as you're willing to pay to have it overhauled if necessary. A diver's care of their equipment plays a big part in how long that equipment will last. Consequently, whenever dealing with used gear I always ask about a diver's personal dive experience as well as why they are getting rid of what they are selling. If the answer is, "it's been sitting in the attic for three years after I dove it a couple times", I'll pass. If the answer is more along the lines of, "I dive a few times a year and just decided to upgrade my equipment", then the odds are better.
Having said that, I have bought all my life supporting scuba gear brand new. I have an Apeks regulator set now that I love, and I would recommend the line to anyone, as there are Apeks regulators for all levels and types of diving, in addition to varied pricepoints. Before you go buy gear though, ask yourself what your goals are as a diver. Tropical, warm water diving? Colder, deep dives? Technical diving? Instruction? You are better off buying a piece of equipment that will satisfy your needs for a while as opposed to something that you will need to upgrade within a year or two. Also, familiarize yourself with different types of equipment styles, configurations, and uses. DIN valve or Yoke? Octo or AirSource? Cold or warm water? All those questions should be asked before you choose a piece of gear to purchase. Then research, make a choice on a few products you want to choose from, and look for a deal on each one. Don't rush into your purchase. Your life will depend on this piece of gear. Your piece of equipment will either enhance or impair your experience as a diver. BCDs are the same way. Technical diving or solely recreational? Are you ever going to dive a drysuit? Do you prefer a jacket-style or back inflate? There are many pros and cons to each, as well as personal preference to be taken into consideration. Talk with a local dive shop, see if they will let you try out some different rental gear. And buy local if you can... the internet is a great tool, but buying online doesn't help support local businesses. Keeping it local will help ensure those local dive shops are around when you need an "emergency" fix, fill, advice, or piece of equipment.