Oh, and NO bad registrars allowed to participate. Snapnames has cleaned up a lot over the years, but they still have some really bad guys on there that they don't seem in a rush to spank (like these TotalNic dudes that have been ripping people off for -14- years now!!) That's so uncool.
Really, if you're trying to make an auction place, if you act fast you can pounce on everything bad Snapnames, NameJet and GoDaddy does. Just see what people hate, and DON'T do it.
Learn from Snapnames that NO bad registrars should be allowed, and customer service should be snappy
Learn from GoDaddy that you shouldn't sell domains you don't yet own yet, and your written customer service should NEVER be dicks
Learn from NameJet that shill bidders and artificial bid inflation ain't cool in a financial market
Frankly, I'd go to Trader Joes and learn customer service FROM them. Be genuinely good to people, LIKE people as human beings, and try your best to make their lives easier. Doing that, you'll make more money than anyone else by far. Most online services really don't understand this. The magic of capitalism is really helping to relieve others of pain and/or trying to help them lead an awesome life, and they give you money for this, and you buy stuff that takes away your pain and makes your life better. When everyone has the other guy's best intentions at heart, capitalism is balls out awesome. It can work well and helps "all boats rise".
Oh... and use UserVoice!! One of the best tools EVER for software development. Bigcommerce was teeny tiny, then they installed UserVoice, and by LISTENING carefully to customers (and having them FEEL listened to), they blew up and became the giant they are today.
Just a few details here, but still worth the (quick) read:
https://blog.uservoice.com/bigcommerce-custom-design-uservoice-site/