Currently: Lighting RuneScape gold maple logs to get from 67 to around 85 firemaking, simply to train some thing, doesn't mean that I can not do anything else. Cash: Around 2.5m like I spent cash to purchase bandos chest and purchased 20k walnut logs. All quest w/o becoming over 1 Def, 50 Atk and 45 Prayer: Assuming you are 1 in the stats when you start...
I strongly suggest you do some prayer based quests continue. If you begin prayer, you won't be good until greater combat (like 75 strength+). If you stay 1, you can pk a lot sooner and help avoid that"all work and no play" issue which many pures do. This helps keep most people inspired. You might also stop at 50 assault for granite mauling first. Remain legit man. 90% of pures (that is a made up statistic, but it's probably unfortunately accurate) nowadays are botted, fight brace wearing nubs.
In my excuse, I am are assuming that you're getting 95 prayer from about 75ish. You are able to add in your own personal numbers and follow exactly what I did to see if its different. So a 35m difference in the purchase price and also a 15 hour time difference. So if you value your time at 2.3m+/hr it's worth it to utilize bark dragon bones. However, this is assuming you have the money already, that you dont, but if you want to accumulate the frost bones to make this possible you can.
Now for the amassing the bones. It all is dependent on how much you make/hr. If you make 2m/hr then it's 90 hours for the frost bones and 72.5 hours for the dragon bones. (Probably not). Therefore it is better in your situation to use dragon bones, by 2.75 hours gap and 35m. Dragon bones are about precisely the exact same RS07 Gold time as frost bones, however you save 35m.