One PC just died. Fortunately, another PC is a cleric that has revivify prepared, an unused 3rd-level spell slot, and 300gp of diamonds they purchased before the session. They cast revivify and bring the dead PC back. The newly-revived PC is grateful and wants to reimburse the cleric, who just spent four sessions worth of gold.
According to the Adventurers League Player's Guide (ALPG):
Rewards and equipment can’t be given to another character, except as follows:
You may lend equipment and magic items to other characters at your table but must return it at the end of the session unless consumed (like a potion).
Characters may choose to divide the cost of NPC spellcasting services obtained during an adventure.
ALPG v8.2, page 3
The revived PC cannot permanently (nor temporarily, I believe) give the cleric PC 300gp. The party also can't do so. Only NPC spellcasting services can be divided. They also can't buy 300gp of diamonds later and give them permanently to the cleric. The PC could probably lend the cleric diamonds to cast the spell, assuming they count as equipment instead of rewards.
Must every PC pre-purchase 300gp of diamonds or a scroll of revivify, just so their clerics don't go broke? What if the PC's death wasn't their fault, so the party wants to split the cost? One final wrinkle - AL tables may have different players each week. An answer that works in a convention one-shot is better than one that only works in a 20-week hardcover.