This thread has been moved to the Item Discussion Forum which is the relevant Forum for asking about RS3 item prices.
As far as your last question is concerned, it is not something you can be advised about on the Forums. Swapping wealth between the games is allowed in game, at your own risk. However, it is a very risky trust trade with huge possibilities of one or more parties not holding up their end of the arrangements, and therefore the Forums may not be used to arrange or advertise cross-game swaps.