Let's break it down a little bit.
First, is an ecommerce company a start up. According to the current generation's definition of start up, kinnnda sorta. A start up is synonymous with growth. Ideally, an ecommerce company should be that, but if it is something that falls into more like bespoke systems, then no, it isn't a start up. Yours sounds more like the product type kinda of ecommerce site (sign up and set up your shop) so yes it would fall into a start up category at some point.
Second, is it tech? Forget being a start up for a moment. Is an ecommerce company a tech company. Having worked in the ecommerce field, I know the answer to be this; you decide whether or not it's tech. The ecommerce experience I had was largely a sales driven one. Tech took a back seat for it. I've consulted for another ecommerce company, whose primary focus was great customer care, followed by online conversion optimization. Their tech interests were limited to customer profiling and facebook ad targeting. None of them were tech start ups. They were just start ups (ish).
This begs a question. What makes a startup a tech startup? For example, what makes medium a tech startup? In their case it's all about the experience of the writing application and reading. Technology is solving tough problems and driving them forward. And that's really it, is technology solving the problem? More importantly, is tech driving the business forward.
In the cases I mentioned, tech was the back seat. Tech enabled us for sure, and if the site was down we'd be dead. But really, it was just a magento site with a custom theme on top of it.
In your case, beyond building out the initial product, what's going to be a primary driver of the business here? Is it all about the marketing? Pushing sales people hard? Being crazy about customer service? Building a product that does some technically amazing things along the lines of data crunching? Thing is, you probably don't know yourself. You might like to think it's all about the product, but at some point you might decide that you've done enough on the product and everything is driven by a 'phone-to-phone' aggressive salesforce. Who knows?
Short answer to your question so far, if you envision fast growth of users, and your business is driven by technology solving real world hard problems, then it's a tech startup and yes, a hacker/techie would get behind it. A start up using tech is not the same as a start up driven by tech. As for interest, techies are attracted by interesting problems. The best way to know if you've got an interesting problem on your hand, is to talk to them about it, and see if they are interested.
Heck, I got behind the ecommerce venture I was in simply because I was using technology to solve backend problems in the company. That's what got my gears rolling.
But all this raises a more serious question. Are you doing this primarily because you are fascinated with the idea of a tech startup? Or are you doing this because you have a real problem that you've (ideally) validated and you want to solve and you need strong technology backing it? You've probably guessed the answer should never be the former. One last note before ending this long comment, don't force your startup to be a 'tech' one.
Maybe it's not and that's cool.