Cool, except you lose 7 million credits on each Type 9 you purchase, and you only have 1 cargo hold to make up for that profit. So multiple Type 9s stored is even more out of the question than a single Type 9 stored.
So coming around to our Narcotics example from earlier: Even buying Type 9s full of 100 credits Narcotics and then selling them + their 10k narcotics later would net you a loss.
Add opportunity cost. Business 101- your net cost is gross cost + opportunity cost
A shielded type 9 (safest) is 496 tons cargo. Every trip you (the original reply person - not the quote above) take to buy a type 9 and move it is 496 tons of transportation logistics lost - e.g. the capacity to move and sell 496 tons of Stuff (TM).
The avg profit even a not-so-good trader is going to make is at least 1.5k CR/ton profit. Translation = 744k CR opportunity cost profit per Type 9 retrieved and moved 1 avg distance segment.
Your 20 type 9 - even if purchase cost was free - just cost you 14.88M credits in transportation logistics opportunity cost to go get them, and another 14.88M to move them to whatever storage location - all assume 1 avg trade route segment distance. If it is longer, we'd multiply this by whatever X factor the distance is greater than avg trade route A-B
Whatever profit you would make in whatever scheme that involves storing 20 Type 9 cargo and then sell it, would have to subtract at minimum this ~30M credit you would have made just by using ONE type 9 doing usual A-B route in the time you used to buy, ferry, and store all those 20 type 9 ships.
If you can't purchase the item you want to store at the same place you buy the type 9, then that is another route segment of lost opportunity cost time. Let's say for argument's sake that whatever you want to store can be purchased a mere 1 avg-trade segment distance from where ever you bought the type 9s. That would add another 14.88M of lost transportation logistics.
So more accurately, you're looking at ~45M credit opportunity cost loss before you've even started the clock on storing and then waiting to sell for whatever profit when the time is right.
9920 tons of stored goods would have to be sold at a whopping 4536 CR/ton profit just to break even with this lost opportunity cost.
And if the background sim were ever fixed to allow this kind of market arbitrage to be taken advantage of - the math for losing all that transportation logistics would also go up, because under a real market fluctuation economy that allowed this kind of stored arbitrage, it would be fair to argue that normal traders moving good routes A to B, would make far more than the sun-standard 1500 CR/ton profit I used in these example calculations.