List fatigue is also a concern. If you're buying a list from a trade show, keep in mind that the other vendors at the trade show, and even businesses elsewhere who bought the list, are also emailing these recipients. By the time you reach the recipients’ inboxes, those readers are going to be exhausted by the barrage of unsolicited commercial email they've been receiving.
Buying email lists doesn't just damage your deliverability and brand reputation -- it can also put your email account at risk. Email clients like Gmail, Yahoo!, and Outlook don't want to be associated with accounts that recipients repeatedly flag as spam. Email service providers like AWeber go as far as immediately closing your account if it suspects you're sending unwanted content.
Testimonials – If you work with contractors or freelancers, you can reach out to them to offer your testimonials in exchange for a link. Moreover, if you are using consultants’ or specialists’ services, you can also do the same as you do with contractors. Lastly, if there are customers who are happy with your product or service offering and they do not mind you linking to their site, this could be a good opportunity for your business.