Hi @Mike-H,
Welcome to the Klaviyo Community and thank you for the tag @Taylor Tarpley!
Klaviyo is free for up to 250 contacts. My recommendation would be to build out a Klaviyo Account (you can mark this as a test account through the settings) and use that for demos. You can even generate some data through the developer tools.
This is what we do at Zyber - we have connected it to a Sandbox Shopify store so we can show off Klaviyo as a tool end-to-end.
Hope that answers your question!
Thanks
David
Zyber is New Zealand's leading Shopify Premier & Klaviyo Master Platinum Partner passionate about helping merchants succeed. www.zyber.co.nz & www.unlocked.co.nz