When I was F2P, I just got off tutorial island some random peron gave me 100gp. I saved up and used that to buy my first good weapon - an IRON LONG!!! :o
The forums do make a small differance but the main factor is autoers. Because there are so many sharks, yew, etc they go doen in price and I think will keep going untill Jagex finds a way to totally get rid of all (or at least most) autors.