The trade amount has been capped at 1m gil since arr. It is time to raise this limit with gil inflation. Many items can be over 1m alone, plenty in the 3m-15m range (night pegasus, eureka mounts, cassie earring, blitzring, etc), and even some up to 50m+ (Wyvre Horn, Fallen angel wings).
Even if the trade limit was changed to 10m, it would help with safer player to player trades, though it'd be nice to have it much higher in general.