That's one way, but if you're already selling a regular line on ebay (as I was when I started here) it's very easy to get your buyers to follow you. I'd made dozens of sales before I spotted my first ebid bargains and started buying also.
It's a better way too. Certainly I'd think somewhat well of someone with +6 feedback due to buying, if the feedback indicated they were easy to deal with and reliable. But I'd think a lot better of someone with +6 feedback due to selling. Clicking on a button to send payment doesn't mean someone's a seller who knows how to describe goods honestly, pack well and promptly, handle questions properly, etc.