The surname product business is a scam. . In Germany unlike in Britain, coats of arms were assumed by individuals. In Britain they are specifically granted by the the heraldry authority.
However, there really isn't any such thing as a family crest. A crest is part of a coat of arms and as Joyce stated they belong to individuals, not families.
Frequently more than one man with the same surname, not all necessarily related, were each granted or assumed their own coat of arms, all different. No one peddler who sells them on the internet, at shopping malls, in airports, in magazines or solicit by mail will have all of them. They don't need to in order to sell. The only time they will have more than one that I know of is House of Names will have more than one coat of arm associated with the same surname if more than one man with the same surname from different national origins were granted or assumed one. Then they will have one of each and there might have been 50 others. At the same time most men with that same surname are not entitled to a coat of arms at all as they have no direct ancestor that were ever granted or assumed a coat of arms.
Not too long ago there was an ad running on TV for a company selling framed surname histories which is somewhat shady as not everyone with the same surname will have the same history. When surnames were taken or assigned in Europe during the last millennium it wasn't impossible for legitimate sons of the same man to wind up with a different surname and still each could have shared his surname with others with no known relationship. The root person of your surname will not necessarily be the root person of someone else with your surname. The man in the ad stated "a" coat of arms will be on it, not "your" coat of arms. You see on TV the FCC can slap a company with a big fine for fraudulent advertising. The FCC has no control over the internet or some merchant in your local shopping mall.
Edit: House of Names has the following in small print
"We encourage you to study the Horstmann family history to find out if you descend from someone who bore a particular family crest . . . . . . . . No families, not even royal houses, can make sound claim to the right to bear arms unless a proven connection is established through attested genealogy records."
The coat of arms they are displaying was assumed by one man named Horstmann. It is up to you to find out if you are a direct male line descendant of that one man. If not it has nothing to do with you at all.