Of course not every transitional form can be dug up. Fossilization is relatively rare, and many entire species have no doubt gone extinct without leaving any evidence that we can turn up. However, it is not necessary to turn up all transitional forms, so long as the theory can be supplemented with other evidence, such as genome analysis (and it can). It is, however, granted that every transitional form discovered adds strength to the theory. So how many transitional fossils have been discovered? A lot. Here's a severly abbreviated list on
the wiki. Here is several hundred pages worth of transitional forms
just for certain fish, and if you read the entire thing I will be very impressed.
Saying that the theory of evolution is unsaisfactory because not all transitional forms can be discovered would, of course, be an argument from ignorance.