I'm all about low budget testing. Two suggestions:
1) Email 20 customers to see if they'd be interested in previewing some new technology that you're working on over a 15 min Zoom call. Chances are 2-5 will agree. Record the calls (recording is built into Zoom). Share your screen. Preview your bot for them, and let them do most of the talking.
2) Grab someone in your office. Depending on the size of your company, head out into the hallway, or outside the building. Find 3-5 people who will stand there and chat with you for 5 min. Hold a screen in front of them with your chat bot on it. Have your buddy stand behind you, and record each session over your shoulder with the camera on their phone.
That's what I would do. Hope that helps!