Currently, no one will even think about buying those super expensive high-end cooking recipes and they're right. Who in their right mind would spend thousands of gils on something that will most likely last 5 min during a wipe. In fact, at the time being, pretty much everyone runs on lvl 30ish foods which are affordable. And even then, a typical raid night will get you to use from 10 to 20 food you bought 200-300 gil each which isnt cheap.

Therefore, this game needs some food, this may be only for high-end recipes, which last through death, perhaps also longer than 30 min. Maybe 1h. In these conditions, getting the best buff for a considerably high price could be considered.