The F# indicates the generation, it doesn't matter if they were pulled from the river/creek/stream/lake/pond in the wild as just free swimming, they still originated as wild fish. If they are to be used as breeders once grown out, they ARE the F0 (wild) breeders, no two ways about it, their offspring will be F1 and so on.
For example, I could go to the LFS and buy 20 convicts to start a breeding program, since they are the first breeders in my program, they are the F0 fish, their offspring would be F1 and further generations would be F2, F3 and so on. The LFS cons are likely nothing more than mixed lineage tank bred mutts, but, I can give them the F0 designation in this case, they are the beginning of the line.
Sorry for following the derail-rail, back on topic. I think that there is a lot of confusion when it comes to prices on wild stock, for example you will rarely find wild Uruguayan fish on our list, simply because it's more effective to bring back the wilds and put them into breeding programs and supply F1 - the cost per fish would be way too high on the wilds. I think that the prices on W/C can be exaggerated in some cases, it all depends on the freight costs and how many stops they make along the way.