Currently: Lighting maple logs to OSRS gold get from 67 to about 85 firemaking, simply to train something, doesn't mean I can't do anything else. Cash: Around 2.5m as I spent money to purchase bandos chest and bought 20k walnut logs. All pursuit w/o becoming over 1 Def, 50 Atk and 45 Prayer: Assuming you're 1 in the stats once you start...
I strongly suggest you do some prayer based quests . If you begin prayer, you won't be that good until greater battle (like 75 strength+). This helps keep most people motivated. You might also stop at 50 assault for granite mauling first. Stay legit man. 90 percent of pures (that is a made up statistic, but it's likely unfortunately true ) these days are botted, fight brace sporting nubs.
In my explanation, I am are assuming that you are getting 95 prayer from about 75ish. You can add in your own numbers and follow exactly what I did to see if its any different. So a 35m gap in the price and also a 15 hour time difference. Therefore, in case you value your time at 2.3m+/hr it is worth it to use frost dragon bones. But this is assuming you've got the cash already, which you dont, but if you would like to collect the frost bones to make this possible you can.
Now for your collecting the bones. Everything is dependent upon how much you make/hr. Should you make 2m/hr then it is 90 hours to your frost bones and 72.5 hours for your dragon bones. Now adding how long needed to use the bones its 97.25 hours all of the way through for dragon bones and 100 hours all the way through for Frost bones. And you need to answer for yourself if 2.75 hours is worth 35m. Therefore it is better in your situation to utilize dragon bones, by 2.75 hours gap and 35m. Dragon bones are all about the same period as cheap RS gold frost bones, however you conserve 35m.