shall i offer to pay for the plumbers time to visit the property and lay a red carpet and rose petals on the floors for such an occasion.
i can tell you think you are the messiah of plumbing and should be compensated for your trouble how ever much knowledge is passed on to us mere mortals.
So you expect a pro to come over, do an assessment, design a system, cost it, and not charge you anything for his work?
I suppose you also call an accountant, get him over to have a look at your books and send him home with the message: "tell me how much tax you can save me, and if I like the amount, you can do this year's accounts." If you don't charge a lot for it.
Or your dentist, take some x-rays, if you find the cavity and can fill it for "a fair price and don't hurt me" I will give you the job.