You don't have the be purely an online business in order to be classed as one. You could have your own store, but it might just be that you generate more sales through the Internet. Or, it might be that you're a new business just starting out, and you're following the growing trend of startups who are internet based.
Conversion rates are one of the most important metrics that online retail businesses need to measure because they show you exactly what percentage of visitors to your site actually buy something. Having a high traffic rate is important but it doesn’t really get you anywhere if your conversion rate is low and all of those people are leaving the site without making a purchase.
Any business that has an office that has a whirlwind of activity will burn through office supplies almost weekly. It's the cost of doing business and being a freelance copywriter but it's not a cheap expense either. It has to be made but you don’t need to be wasteful, even if it's just everyday equipment you are buying.