Updated: Oct 27, 2018
The cheap/ slow method is to craft Gold Bracelets all the way from level 7-99, and you'll make yourself 60mil. Just kidding. That is way too slow. You'll be getting 20 000 XP per hour if you did that. So, instead, from level 20-46, you should craft 1200 Sapphires, costing you only about 400 000. Then, from here, there are three ways you can go about crafting.
The first way is to craft unpowered orbs from levels 46-87. You'll need to make 70 000 unpowered orbs, and this is going to cost you about 9mil. But, you'll be getting around 80 000 XP per hour.
The second method is to continue cutting Sapphires, 78 000 of them, to level 87. This is a lot more expensive than unpowered orbs, but you'll be getting about 1/3 more XP per hour. It's going to cost you about 25mil to cut Sapphires all the way to level 87.
Now, another method, which I recommend a lot more than the other two that I've just spoken about..From level 58-87 you should craft 41 000 Diamond Bracelets, which is only going to cost you 6mil, and you'll be getting 90 000 - 100 000 XP per hour.
Now, you can continue crafting these all the way to level 99, but there's actually a faster and cheaper method than that. From level 87-99 you should craft Empty Light Orbs, 140 000 of them, costing you only 18mil from level 87-99, and giving you 120 000 XP per hour.
The alternative, which is a bit cheaper is to craft Dragonstone Bracelets from level 74-99, costing you only 10mil to get to 99 Crafting, and 140 000 XP per hour.
Now, you're probably thinking "Why didn't I just use that method instead of the Light Orbs?", which are double the price almost. Well, the Grand Exchange prices are really, really unstable for Dragonstone, and the supply for them are really, really low. So, it's really hard to get your hands on a lot of Dragonstone for a good price.