Many sites like SettlersOnline Wiki have posted loot tables that are pretty much spot on. Using this info, we can calculate the expected value and the exact worth of a loot spot.
For example, here's Roaring Bull:
We are guaranteed to get one of the items in each of the slots. Out of slot 1, we will get either granite, exo wood, titanium, or salt. Each of these commodities are readily traded (here's a price guide for Zues). For this example, we'll use these values:So, we have a 26% chance of getting 1000 granite. If we were guaranteed to get 1000 granite, then the value of this slot would be 3.75 X 1000 or 3750. But, our chance of getting 1000 granite is actually only 26%, so our "expected value" is .26 x 3750 or 975. Carrying out the calculations for each item on the loot table, we get something like this:granite = 3.75
exo logs = .35
titanium = 3
salt = 7
So, the total value of a RB loot spot is 5313.