I do agree that it was a bit sneaky to change the total worth to extra worth needed. Not that i'm having a go at DA, oh no
(please dont infest my ship with a plague of bounty hunter...)
The problem with net worth going up and down seemingly randomly when you buy stuff is that it calculates the value of your cargo based on the average price for that commodity.
Say there is a commodity which varies in value from 500 - 1500, say Luxury Goods. If you buy 10 unit of LG at 500 you lose 5000 creds but as the average value is 1000 you gain 10,000 net worth because that is the average value so when you buy you will see your net worth go up 5000. This is why you sometimes level up just by buying stuff. Similarly if you had scooped 10 units of LG your net worth would go up 10,000. However if you offloaded it for 500 a piece your net worth would go down 5000 (lose the 10,000 + get 5,000 creds).
Does anyone know whether the average value is the universal value or the average of the prices you have found so far?