No super website IT magician required... I have over 30 vendors bookmarked and I do business with about six of them. The one thing they all have in common? A single line of text, either at the top of the page or embedded in a header graphic that simply says "
All orders over $___ ship for free!" or "
Flat rate shipping on all orders only $xxxx for a limited time."
That's it. I know how large my order has to be to have shipping be ZERO and this in turn encourages me to spend more... with THEM... before I ever stick even one thing in my cart.
Pet peeve? Vendors that advertise an item on sale or "New!" but don't tell you it's sold out UNTIL you try and put one in your cart!
Makes me happy? Vendors that tell you it's out of stock
at a glance. Even happier? An actual count of how many units are left in stock, especially in regards to hardware... "Oh, look! They have all the colors *in stock*, even purple!!!" OR "They have all the colors, 195 of the blue but only 3 of the purple ones the wife wants are in stock! Better hurry up and order NOW!"
Even happier?

A short list of products I have recently looked at on their website and to compliment that perhaps a list of suggestions like "Similar products you might be interested in." or "Others considered this one as well."
Pet peeve? Vendors that have a poor sense of inventory categorization, right at the home page. A study was done years ago, when I was dabbling with web development, that basically indicated that you loose something like 90% of your page's visitors after the first click and then 90% of what remained of them at the second click and so on. A website that makes it next to impossible to find what a potential customer is specifically looking for will not get as many sales as one that is easy to navigate. Same thing goes with trying to list every single item you have ON the home page! That's called an "index" folks and is usually found at the back of a book, for a reason. Take the book analogy one step further and have the home page be a clean, easy to read "table of contents" with a short list of general but concise categories instead, i.e. "e-juice", "starter kits", "atomizers", "cartomizers", "advanced PV", "accessories", "batteries and chargers", etc.
A website "Search" option is nice to have but no one should HAVE to use it to find what they are looking for! (Yes, there really are some vendors that have what I want... but you wouldn't know that without playing detective for half an hour.)
Last but not least... OK, I know business is booming and you are super busy. Great for you! But honestly, your website is the heart of your business (unless you do the majority of sales out of a B&M... which might indicate the problem even more clearly!) Spend a little quality time UPDATING it, at least once a week, or pay someone to do that for you. One of my favorite vendors (who shall remain nameless) ranks up there for me for several reasons... but their inventory changes so rapidly, including new additions, that I am often left feeling like I need to harass them with a phone call every time I order because the website is so out of date. Vendors? Don't be "that guy", please.