When deciding to choose a new pet rat, you're generally going to have to decide whether you want to go through a standard pet store chain, which is probably where most people would acquire one, or if you want to go through adoption, or if you want to go through a breeder. And generally I think that those are the three categories or the three places where somebody could acquire a new pet rat.
If you choose to go through a breeder, generally it means that you're looking for a very specific breed, a very specific variety or type of rat, or even a specific color pattern or color mutation of the rat. And breeders can be found both through local rat clubs, you can often find breeders by going online and doing internet searches, as a means to find them.
The majority of people probably are getting their pet rats through rescues. There are a lot of rescue organizations. There are a lot of people who choose to take in unwanted rats, who take in litters of rats when somebody unexpectedly has one, or the rescues will often acquire the rats through hoarding type situations, which is an unfortunate aspect of what sometimes happens with these animals, and they'll take in a large number of them, and then have to go through the process of rehoming them.
Otherwise, people will sometimes go to the pet store to find a rat. Sometimes the rats that are available in pet stores are actually there, and intended to be sold as, food for reptiles, like snakes. So, sometimes it's most ideal to consider going through adoption, going through a rescue organization, to try to pick out the type of rat that you want.
When looking for a rat, generally you want to find one that's happy, healthy, looks contended, is social, doesn't appear to be fearful, looks like it has pretty clean, healthy-looking eyes, no nasal discharge, no trouble breathing, overall appearance of that rat looks like a generally healthy animal with a well-maintained coat, normal activity, normal alertness, and find what's most appropriate for you. Most people choose to adopt a rat that's younger, that way they can socialize it, that way they can handle it more, that way they can raise it in the way that they want, and have it used to their home life and to their environment.
So overall, when choosing a rat, look for a healthy animal, decide if in fact, you need a specific type of variety, but most people don't. You can generally check online or check with local rat groups, check with local veterinarians that see and treat rats, and try to get put in touch with rescue organizations, sanctuaries, or generally people who do pet rescue, that may have a number of rats available for adoption.