The Value of State corps increases with sustained profitability. Look at the Value of State corps in C3's. They are fully upgraded and at default tax and supply.
Ignore any that have a value less than 100B or a new corp star.
My numbers are approximate.
If the value is less than 150B the corp will probably loose money most of the time.
If the value is 150B to 250B the corp will make some profit (less than 0.5B) most of the time.
If the value is 250B to 400B the corp will make good profit (0.5B to 1B) most of the time.
If the value is over 400B the corp will make great profit (1B+) almost always.
A product being in shortage will not guarantee a profitable corp.
A product's price needs to be in the top quarter of it's range for the corp to be profitable. Some products are locked into a shortage/surplus cycle and the price never rises enough for the corps to be profitable.