I can sell you an upgrade for 27M I am one of the biggest/most trustede sellers here. You won't have very much luck buying at 16M however since the price of GP is quite low right now. It will either take a very long time, or most sellers will be scammers.
If you have so much wealth why not pay a regular price to get a faster, safe upgrade with no hassle from me
He is right my friend, nobody is trying to hassle you but Yoho is good people around here. Where RSGP is down to anywhere from 0.20-0.30 per Mil now, prices on upgrades and other things have went up.
You MAY find someone that wants to sell that low, but be very cautious because there is a good chance its a scammer.
I have a 100 day card I am selling right now, for 80M if you're interested, comes with a special pet you can redeem and everything.