The price Changes regularly, but you will find yourself buying it for around 3M GP.
Yes! 3,000,000 Gold Pieces. It looks like it is a lot, but after giving you financial education you will see how easy it is to achieve this amount of money through your money making capacity.
So, Let's Start...
The First Step to accumulate great amounts of money is by buying membership bonds. "Free To Play" Players don't make as much money as "Pay to Play" Players.
Because you get more opportunities to make money by being a member, trough new quests, skills, items and Monster Drops. So, put this in mind: You need to get that Membership Bond No matter What... Otherwise Forget about The money.
The Real money making happens by being a member.

Now I Will give you some options in order to make 3M GP:
1. Skills: If you want to make money while gaining XP this method is recommended for you The only skills I recommend are: Magic, Mining and Woodcutting.
- Magic (Level 44): You should do high level Alchemy on items. The process is simple: Buy "Nature Runes" And an "Items to Alch" at the Grand Exchange but make sure that the alched value is higher that the Nature Runes and The item you decided to Alch Combined in order to see which items you should alch look at this Calculator: http://alchmate.com/
- Mining (Level 10 Recommended): You should mine Clay. Bank them and repeat the process. After having a lot of them, you should add water to them and make "Soft Clay" Cause you will make more money out of it.
You can also mine iron, but it will take more time. And time is money.
- Woodcutting (Level 60) Chop down Yews... As simple as that.
2. Picking Item in the Wildernis, or in random places. See this Video: Check out this video.
https://www.youtube.com/watch?v=pt3lT2tu-C0