any gold site / seller?

that accepts paymo or something that changes via cell phone?

 

I have never seen such a thing in my time playing runescape
Only payment i have ever seen by Mobile/Cellphone is Runescape membership.

Vast majority of Gold sites tend to only accept Paypal WU & Bank xfers
I do like your idea, although i don't think there is anything out there at the moment which accepts it.
Good luck, if you do manage to find one Let me know As i like the idea.

 

I could if you would pay enough, do not expect for the regular prices.

 

The fee's for this are extremely high, that's exactly the reason why sellers / buyers normally don't use this.