Crystalline LSD is like the pink elephant in the room, it exists and god damn is it strong. It technically is the strongest form of LSD because it is the purest. However to buy a crystal of LSD would cost what most people would consider a small fortune. You don't just buy a single dose of crystal.
This statement doesn't make logical sense. Crystal LSD is just LSD that hasn't been diluted in liquid, spray / soaked on blotters, or introduced to another medium for appropriate dosing yet. It doesn't make it any more or less pure.
100ug of LSD crystal (which would be impossible to measure with consumer-grade gear) is no more pure before mixed with a drop of liquid.
Crystal LSD is of varying purities, just as blotter and liquid LSD are of varying purities.
Typically crystal LSD is "newer / fresher" than blotter or liquid, and therefore potentially more pure, but that's not a hard and fast rule either.
To the OP I would suggest that if you don't know for sure if you can get crystal LSD or what it should cost (ie, the most expensive gram of drugs you ever heard of), you might not be getting the real deal. Crystal LSD is rarely sold in units less than a gram, which typically produces ~10,000 doses and is a sizeable investment.
Somebody mentioned something about having to know or be close to the chemist to get crystal LSD. I've never known this to be the case. I haven't had LSD in years but back in the day there were a number of people in my circles who would obtain crystal, and they certainly never knew anything about the chemist. Crystal LSD is not that rare if you have the money for it and demonstate enough interest in getting it, and you show yourself to be a relatively trustworthy individual, you can find it.