I'm sick of all the bullshit 'estimate' answers that get posted on this board. If you don't know the answer to a members question to within 10-20%, don't be a post count whore. Your little stories about what 95 or 99 prayer cost you are not relevant due to the fact that they weren't achieved at today's prices.The mods need to crack down on this.
The correct answer to your question, at today's prices is:
You need 8635000 experience points to get to 95. Dragon bones give 252 experience points each at a gilded alter. Thus you will need 34265 dragon bones.
Dragon bones cost 3268 coins each (market price today). However, they are dropping, so factor that in to the final cost.
34265 x 3268 = 112 million coins.