One reason folks who have real shops (brick and mortar I mean) and then also have a presence on
ebay or also their own web-site is to advertise.
If you are not on
ebay at least a bit you and missing part of the market.
I agree that there is a place for all forms of stamping shops as there are all kinds of people plus all kinds of stamps.
I read a little note somewhere about Canadian shoppers who like to use
ebay to research and price goods but would not buy there. They wanted to see (and feel and taste etc) the real thing and have the surety of dealing with a teal person. There is much to be said for that way (I can't help it I'm a Canadian too!)

But then there are folks who view
ebay as their chance to get a great deal that they would be supposedly overcharged for at a real store. It's a matter of perspective.
Good advertising and salesmanship will help to lay to rest many qualms and fears of internet buyers and also real store buyers. For example some (many?) internet stampers prefer the limelight and dislike dealing with real folks or even being in public.
There is also the factor of saving time and shopping or researching when you like to as you like to.
There exist programs of rebates on
ebay, for example, where if you refer someone from an outside site to
ebay you will get a credit somehow from
ebay to your store there.
There is the price of overhead. If you can't have the clientele or location to draw lots of constant customers and also the impulse buy drop-ins then you have to make it up in some way to cover expenses. Sites like
ebay or other online sites (straight sales or auction) are one way to access the growing number of people more comfortable with buying online.
These buyers percentage of the whole lot of buyers may change by country or region also. I am always surprised and delighted when I get a buyer or even bidder from a far flung corner of the globe. I have sold France Ceres and Napoleons to someone in Terra del Fuego at the tip of southern Argentina, Canada stamps to a lady who collected royalty on stamps in Nunavut way up North in Canada and cigar revenue labels to a fellow in Moscow, Russia (I Googled mapped him and had an enjoyable look around his neighbourhood).
There are different levels of risk about different aspects of selling online as apposed to through the mail (which is really what
ebay is, online but international mail order) or a bricks and mortar store or shop. You always have to have your common sense about you and always have to make judgement calls about who is good to deal with, buying and selling.
There is also the thought that in order to be successful on
ebay (and probably elsewhere too) you must advertise and draw people to your store (or sales) just like in other forms of selling. If people don't even know you are there how can they even look and then buy or bid?
Advertising on sites such as this is one example. Look at the one little ad at the top of the screen here. I don't usually click on any of them but sometimes I do. If it wasn't there I wouldn't.
It is a lot of work no matter which way or ways you choose. There are always learning curves and getting to know the ins and outs of how it all works. I have been at
ebay for years now and feel comfortable there as I have gone through most of what can happen on there and so have lost my fear of the unknown.
Now I am starting to look more and more at other sites like Delcampe and BidStart and Wensy and even selling at the local stamp club (I don't enjoy crowds so was avoiding that) or shows or sitting there in my little chair as the cruise ships come in with all the tourists (haven't done that one yet) (I can't believe how many people come in to port here now on some big ships, the Queen Mary II etc) (note to self, make personal stamps of visiting ships).
I think a good idea is to try
ebay or something out in a small way to get comfortable with it and see what you think and get the kinks out. You have a web site, and if that is your main selling venue then that is OK too, but learn about advertising around on other sites worldwide even just to get the word out.
I find also that absorbing all that information out there in books and on the internet is best done along-side actually doing the things also. can't learn if you don't make mistakes. Of course one must consider one's own comfort level of the risks involved too.
That is one reason prices are higher with established sellers. They do have to cover the expense of loss and insurance in different ways. If I sold 10 stamps to make enough to buy one stamp but then lost two stamps it wouldn't work out at all. Common sense again. Adapt and survive. Not really the survival of the fittest but the continuance of those with the confidence to know they can adapt and change to meat the changing circumstances and prevail over the odds. Which you have done already so you are laughing, so to speak. You know how to do the hard parts already.
By the way did you get my through SCF email to you about the Canada stamp?