What are my options for selling my system?

I purchased a SimpliSafe system (SSCS2) about 6 and a half years ago, along with 6 extra sensors (SSES1), 2 smoke detectors (SSSD1), and 2 carbon monoxide sensors (SSCO1). I never used any of it. I never activated my service. I think I may have opened the box it was shipped in, and that's about it. Considering it's age, is it still worth anything? If so, what would be a reasonable asking price for everything? Is there anything I need to do to "transfer," or would I simply mail everything to the buyer and be done with it?