You have a chance of getting free sex via WYP, or at least a lot cheaper than punting, if the woman takes a shine to you, but you have to approach things in a different way to punting.
In punting you are there for one primary objective and she knows it.
WYP is like dating in that you can't rush in like a bull in a china shop but have to come across in a very gentlemanly manner and charm her, and then hopefully she will enjoy it enough to want to meet you more and eventually give you sex.
Be careful about the amounts - ensure you set your own limits and stick with them, and that will turn away many but you don't want those ones anyway.
Same with SA, but I find WYP friendlier.