Irrigation Field & Billing Workflow help!

I am not in irrigation, but as an outside perspective I was also confused as to what you would be charging for if it was free (before I got to the bottom). I think there are many options here, but two that stick out to me. 

1. Clearer communication with these clients. “It’s a free check, you will not be charged for travel or our time to go out there and do the check. Often our “VIP” Clients like for us to do any repairs needed and just bill it if it is under $500. Is this something you would like for us to do? Or would you like for us to create an estimate and send it to you for anything we found and schedule with you to come back out?” With this, they completely understand and can know what to expect. Most will probably say - yeah go for it. Some will say estimate, and that’s fine. You will charge them accordingly for time and travel, etc.
2. If you aren’t ready for step 1 (zero judgement by the way!), you could just switch to creating the estimate and sending it out to them to let them know what you found. Once the client approves, you can offer number one above. “What we find with many of our VIP clients is that they would rather us just repair it while we are there as long as it is going to be under $500. Would you like for us to do this for you next time?

Hope this helps! This is just my opinion, hopefully some others chime in!