There are several options to consider when buying a tarantula. You can choose the most suitable method of acquisition based on your preferences. Below, I list the various ways of acquiring a tarantula in decreasing order of suitability, based on my personal experience. (note: I am writinh from position of somebody from Czech republic)
Buying a tarantula from a breeder or at a expo.
I consider buying a tarantula from a breeder as the safest way to acquire one, both for you and the animal itself. This can be done either by visiting the breeder at their home or at a expo, which regularly takes place in major cities in the Czech Republic and I think in the other states too. First and foremost, you have the opportunity to inspect the animal before purchase, ensuring that it meets your expectations and appears healthy. Secondly, you can safely transport the tarantula to your home on your own.
Buying with shipping through a transportation company.
In our conditions, it is common for breeders to send spiders through regular shipping services (such as Zásilkovna or PPL) and if everything is done correctly, in the vast majority of cases, the spider arrives at your address unharmed. The most important thing is high-quality packaging, taking into account the season and delivery speed. Zásilkovna is the most frequent choice, as the spider usually arrives the next day, but there is still a risk involved that you need to consider. You can simply purchase a spider to be sent from someone in themed Facebook groups or on the animal classifieds website iFauna.
For me, this is not really an option. Although some large retail stores offer tarantulas, I wouldn’t buy one there on principle. They often can’t tell you the species, exhibit tarantulas in unsuitable terrariums, don’t provide qualified advice, and the price is oversized compared to the tarantula and the catastrophic service. Selling live animals in pet chains is a horror, from my point of view bordering on abuse, so even though you can’t really speak directly of abuse in the case of tarantulas, I don’t recommend buying them at these places on principle.
An exception may be some specialized exotics shops, where the care of animals and the qualifications of the sellers may look different, but I don’t have a personal positive experience.