I'd just sell what you dont use? If you still play rs regularly and find it fun than keep like 700m ( good fun amount ) and sell the rest. you can easily have fun with 700m and show off

and have $500 extra in your bank. But if you have a job than i guess $500 isn't to much....you could always keep it until your absolute bored of rs ( just make sure you don't lose to much ) and if gp doesn't lose it's value than you can sell it at ANYTIME. If i were you i'd do that.. i'd also buy 3rd age melee , 99 herby, and 99 pray ( baby drag bones - slighly cheaper)