Well here goes.....(first of all you need GF Alexander *and Tonnberry)

1:Using MedLVUp turn all your tents into megapotions.

2:Now(you need Haggle and Sell High for this) Buy 99 more tents and turn them into Megapotions as well, and just keep doing this until you have 99 megapotions.

3:Sell the megapotions and use the gained profit to keep repeating the process.You shoulg gain somewhere
bettween 100,000 and 200,000 gil.

4:Having the ability call-shop speeds up the process heaps.(you dont even need to leave the ability menu then)

Well thats all I got for now.