I can add a few things...
One of my favorite places to look online is Drs. Foster and Smith because not only do they sell a lot of the things I need, but they also provide educational data for each and every fish, provide helpful tips on how to run your tank, and pretty much try and educate you in every way possible. That being said, there is still room for improvement with any place.
I love scouring YouTube for educational videos. It would be nice to see a retailer help fuel the educational videos available with many at their site. They should be complemented with thoughtful and informative reading material as well. Reading and pictures are great, but videos help turn those mental and 2-D images into something more tangible sometimes.
While on the topic of videos... Video tours of the site would be nice as well. One of the things we can do with our LFS is see how they operate, but online vendors can be a mystery. Sometimes it is frightening buying from the mystery box.
Heck, I'd even like to see videos of the fish and corals that are for sale! I've been formulating a plan of something I was going to propose to Drs. Foster and Smith that I'll share here too. A 180 degree photo booth tank that takes multiple pictures, Matrix Style, of their corals that are for sale that then can be compiled into an image that when you mouse over it can rotate the coral from one side to the next.
Ok... Back on track...
It's a digital world, and things like Skype make communication via video so easy these days. It would be nice to be able to Skype with the online retailer whenever a large investment was being made so that the purchase can be visualized pre-shipping for final confirmation.
Look at me go, pushing the envelope! I do it because the technology is here, but it is not being fully taken advantage of yet. I mean come on! Doctors can perform surgeries over the internet for crying out loud! let's get with the times!!! And don't blame cost... Things like Skype are FREE! I make decent videos on my smart phone that cost $50. There are ways to be technologically advanced and competitive without paying a fortune.
I suggest working with local manufacturers and suppliers that can help you engineer and design your own line of things like Sumps and Overflow Boxes and Custom Tanks if possible. Providing options that aren't available elsewhere might give you something that becomes sought after, that is, if you can design something really worth while for the cost.
Take advantage of something like Kickstarter.com to maybe start funding your endeavor. I know I might be willing to contribute a small amount of something if it meant I got a free frag of something really nice (not cheap like a green star polyp or a random button polyp) later down the road. Sure, maybe you'd be practically giving away a slightly expensive coral frag, but if it helped establish some start up capital it might be well worth it.
Maybe there is a LFS or local Craigslist sellers you could partner with that don't want to take the time or extra measures to be fully online as your are attempting. Sell their items at reasonable prices and split the profits.
If you get to the point where you start having great success, start branching out to nearby LFS in neighboring cities that you deem worthy and hand deliver sales through them so your buyer can observe it in a tank before purchasing.
That might be too complex. Just brainstorming out loud there...
Good Luck! Competition with quality products and services is only a good thing for us!