There are good online store building solutions like Shopify, Volution, etc.
I'm looking to build my own small-scale service like that.
Are there any customizable online store building scripts I can install on my own server or companies that offer reselling opportunities?
VirtueMart is another very simple e-commerce app that my clients have used very successfully. It's based on Joomla, but still is an effective and easy tool to deploy.
I'll warn you, there's not a ton of money to be made building e-commerce "services" to resell. There's a million and one people doing it and it takes a LOT of work to get right. Not to mention the heartburn that goes along with payment processors and dealing with fouled transactions, which happens to the best of systems. People don't have a ton of patience when it comes to credit card transactions and I found myself doing tech support at the worst possible times. These are HIGH MAINTENANCE apps if you're not just doing it for yourself...