If you would like to sink most of RS gold your cash into one, definitely receive the SGS. You can get two specs per bar, and if you utilize piety during that time then it can heal quite a lot (Prayer points and Hitpoints) and I discovered each spec averaged to revive a bit more than a shark. However, it is not completely trustworthy and you'll likely still need to attract some food, simply not as much as you'd have before. The BGS has it's own perks also, but not quite as good if you're just training on a standard monster.
Next, I'll be cooking Swordfish from 86-90 Cooking. So figuring I need to cook 12,490 Swordfish to go from 86-90 Cooking, it is going to cost me only 312,250 since 12,490*25 equals that. My 3rd step will be cooking Monkfish from 90-94 Cooking. My last step is Sharks from cheap OSRS gold 94-99. They are a 46gp gap so cooking 24,238 will just shed me 1,114,948. Please tell me if I calculated this particular right.