It happens that in the Ooniverse the same kind of thing happens here and there... here's one fully reproducible recipe, to show you can make easy money if you already happen to have a good amount of Credits.
First of all you need 2 OXPs - Galactic_Navy and ShieldEqualizer+Capacitors. Without the second one, you might get similar, but much smaller balance increases.
If you're a wealthy Commander and likes battles, you've certainly already purchased the 'right' amount of Navy bonds - so as to get the 75% discount on the Navy's twice-as-high original equipment prices (which in the end, equates to a 50% gross discount over every one else's prices).
Also, if you're a wealthy Commander and likes battles, you've almost certainly fitted your Iron Ass with a Shield Equalizer, which carries the hefty list price of 75000Cr
. The interesting point here is, being the Equalizer one item of superior quality and superb craftsmanship, it also comes with a no-questions-asked 90% money-back guarantee. 
So, you get the picture. A Navy supporter with maximum discount can purchase the Equalizer at a SecCom station at 37500Cr
. And, whenever and wherever he wishes, return it for a refund of 67500Cr. 
This a simple buy-low-and-sell-high operation, fully legal and (still) supported by all parties involved... the return-for-a-refund operation can even be done at SecCom itself, 5 seconds after the original purchase, and maybe even repeated ad infinitum by really greedy Commanders.
Of course, an experienced and smarter millionaire, one who knows how the market operates, won't try to kill the chicken of the gold eggs by repeatedly abusing this opportunity... but he certainly has nothing to lose, for instance, by repeating this simple operation at a slower pace, such as at every other visit to a SecCom station.
Cheers
I finally decided to 
! I'm looking forward to its addition to Oolite... money won't be a problem, of course. 
