A diverse set of companies is doing big business selling cheap online goods and services across the web.
Apple has sold more than 6bn songs for $1 apiece on iTunes.
Skype took in $550m last year selling cheap internet calling minutes.
您已閱讀11%（232字），剩余89%（1950字）包含更多重要信息，訂閱以繼續探索完整內容，并享受更多專屬服務。