Yes, I stole the bone calculator, but with a particular purpose in mind. You'll notice that no matter what we come up with in terms of analyzing the efficiency of training the Prayer skill with bones of various kinds, the numbers always favor the cheaper bones, and you and I and any noob who can bury more than 3 kinds of bones all know that that's not how it's done -- you buy the best bones you have the budget for!
To be extreme, if I had a bank full of Santa Hats (I wish!), which would I buy to train Prayer as fast as I could, and especially with the least grinding and Carpal Tunnel Syndrome? The Frost Dragon Bones, of course! So why do our numbers say that I would be an idiot not to buy the normal bones? If I'm poor or lazy, or fresh out of Lumby, I kill, bury or buy whatever I can, and I'll be very glad for the XP anyway. But why buy a ton of normal bones just because they're cheap? A single million of gp buys me something like 10,000 bones! I'll die of old age before I grind them all, much less worship at the Ectofuntus! I can only buy 70 or so Frost Dragon bones, but at least I can use them! So how many normal bones would you take in trade for a FD bone? Away from the G.E.? Right there at the bone grinder or the altar? It'd take a lot, wouldn't it, if you agreed at all, at any price? You bet it would.
So my next question is, is this a product of how we analyze the prices, or is this the result of how Runescape prices are capped (until the 1st, and then we may see something else)? If these numbers don't make more sense sometime after the market caps come off, then we will have to assume the former, and I don't see the math that makes that work, not with the prices as they are. The price of bones reflects the standard "gopher" or "fetch" price of about 100 gp per item, but then that means that FD bones are severely under-priced, or so it would seem to me. Maybe the demand for bones that expensive isn't as high as I think it is? Possibly, but I don't see it. Let me know if you have any ideas, and we'll watch the G.E. in the meantime!
First Formula (gold): (XP X 10) - Price = 0 [give or take]
Second Formula (XP) : XP - (Price/10) = 0 [same]
The XP rate for Herblore, Construction, Summoning, and yes, maybe Prayer too, would obviously push higher, as there are fewer cheap ways to train these skills with any speed. Taking the first formula, we can then use the rather precise Efficiency formulas and the idea of value of time to figure out the best way to train a particular skill. (The only thing that bugs me about the Efficiency formulas is that they don't account for the value of XP, and only budget for gold. This leads to cheap but slow training, and missing out on higher incomes at greater skill levels. I harvest Coconuts with my Giant ent Familiar along, so I know that training skills on the cheap may be penny-wise, but seems to me rather pound-foolish. Sorry.)
For example, you could attempt to train Construction at the fastest rate that the XP tables allow, but this would cost a total of billions (or is it trillions???) of coins to do. As no one I know has that kind of earning power, this obviously is out. But given a certain rate of income / value of time, the best and fastest method should pop up in front of you and wave hi almost! So that's the progress I have now, and leave me a message if you see anything in this.
Bone Experience Cost Cost/XP Cost/XP (Ectofuntus) Cost/XP (POH) Members-only? Bones 4.5 90 20 5 5.92 No Wolf bones 4.5 1,385 307.78 76.94 88.15 Yes Burnt bones 4.5 558 124 31 35.64 No Monkey bones 5 406 81.2 20.3 23.39 No Bat bones 5.3 188 35.47 8.87 10.31 Yes Big bones 15 441 29.4 7.35 8.46 No Jogre bones 15 904 60.27 15.07 17.28 Yes Zogre bones 22.5 685 30.44 7.61 8.74 Yes Shaikahan bones 25 3,424 136.96 34.24 39.17 Yes Babydragon bones 30 831 27.7 6.93 7.95 Yes Wyvern bones 50 7,024 140.48 35.12 40.16 Yes Dragon bones 72 2,187 30.38 7.59 8.69 Yes Fayrg bones 84 6,433 76.58 19.15 21.89 Yes Raurg bones 96 56,761 591.26 147.82 168.94 Yes Dagannoth bones 125 7,036 56.29 14.07 16.09 Yes Ourg bones 140 17,133 122.38 30.59 34.97 Yes Ourg bones (General Graardor) 140 7,234 51.67 12.92 14.77 Yes Frost dragon bones 180 10,498 58.32 14.58 16.67 Yes