Pay builder for estimate?

[NewNameForMoving]

I had a builder visit a house today that I am considering buying. He probably spent up to an hour of his time when you take into account getting there, looking at the best way to do the work and sending me rough prices.

I know it's not the norm for builders to charge for quotes but given that if I don't buy the property he gains nothing from it, I feel as though I'd like to pay him for his time. Would this just be really weird?

Not weird at all to pay him for his time if thats what you want to do. Especially if you don't buy the property.

It is unusual as generally people looking for work will estimate but be in competition with others doing the same
Builders expect that
Builders can’t expect to be the only ones tendering that’s not how the market works

Assume he knew you didn’t own the property at the time aswell.

Yes he was fully aware of the situation. I'm hoping I might be able to buy the property as long as the vendor accepts a below asking price offer, but with the way house buying and selling goes (I have a house to sell and the current owner of the new house also has to buy a new property) nothing is guaranteed.

and if you do buy I would suggest you get several quotes for any work needed.

As you are only considering buying the property I would say that in this particular case, it would be fair to pay for the estimate.

When tendering for work it is completely the done thing to obtain multiple estimates and then go with your chosen supplier, this is known and accepted and anyone asking for payment for an estimate would certainly be unusual (and shooting themselves in the foot).
In this case though, it isn't a competitive tender you are asking him to provide as no other builder was there, it was really his professional advice with a price thrown in.

Pay him for his time. Good builders are difficult to find. Look after him now and he will help you in the future. Take for granted now why will he want to work with you later?