~1 Million GP (1k Burst's) = ~200-250 Crimson charms.. You'll need like 25k Crimsons to 99.. (Crimson alone, Say, 20k when using all gold, green and blue aswell, possibly less). 4-5k casts (4-5m) is 1k Crimsons.. That means ~100 Million in bursts alone to 99.. Not including shards + second.. Only the bursts to 99 (in Crimon charms). Shards and seconds will cost about the same, so you can assume much more than 100m to 99 (close to double, if you make all the best pouches you can to 99).. So 92-93 is about half of that (92 is almost exactly half the XP remaining until 99), and with the shards and seconds, should leave you somewhere around your 90m budget.. Completely and utterly estimated.. Just try for yourself, as there is no sure-fire answer.