Spores are, to some, an allergen and a nuisance. But to us mushroom growers, essential.
When it comes to growing mushrooms, one of THE most important choices we have to make is our source of spores. It's even more important than the specific strain.
Harvesting spores, to make prints and syringes, is easy. Doing it without introducing contaminants is very difficult. The mushrooms must be grown in a clean environment, harvested before the veil breaks from the cap, and the spores collected on a sterile surface. The water used to make the spore solution must be sterile, and kept sterile the whole time.
The thing about spore solution is that it is not sterile. It can't be. If the spore solution were sterile the spores would be dead. The key is that the only "contaminant" in the spore solution, must be the spores we want.
If you are looking for oyster, shitake, or any legal type it's easy. There are whole businesses that focus on keeping high quality genetics alive and available for commercial farms. But in an era of prohibition and the war on drugs, there are few institutional quality producers of magic mushroom spores. Most reputable vendors in the USA buy their spores from the Netherlands or Canada where there exists many underground labs.
A good way to find reputable vendors is to search forums for reviews. Better yet, look for a historical track record of positive reviews. TheShroomery.org has a list of trusted vendors, and it's easy to search the forum for user feedback. Buying on markets like eBay or Etsy is a fools errand. Those are likely produced in someone's basement in less than ideal conditions and should be avoided.