How many seeds is a good amount for a trade?

I was wondering how many seeds someone would expect or want of a certain plant to constitute a good trade?

I think it depends on what your trading. I always try to check with the person I'm trading with - that way there's no chance of messing up!

Usually they say 25 seeds but I always send more if they are really small and less if they are tree seeds say 10.

Thanks Honibee