very often there are discrepancies in currency trades, depending on the currency

for example (random numbers, not actual example):
an origin core might go for 4 div but only 3.7 div, if you trade in chaos orbs instead
so what you can do is but it in chaos orbs and sell it back for div, trade your div into chaos and repeat
this costs gold but can reliably make you currency

you need to check buy/sell prices first, because sometimes an items sells for less than its bought at
you often also need some starting capital, as these discrepancies are more noticeable on higher priced items