The main options are nucs and packages.
A package is a bunch of bees in a screened box, usually 3 lbs. A queen is included in her own cage and a can of syrup is usually included too. These are made by dumping a bunch of random bees in a box and adding a queen. The queen is not related directly to the bees, and in fact have come from different hives. You know virtually nothing about either. Your confidence in the sale is directly related to your confidence in the seller.
A nuc (or nucleus hive) is a small hive, usually five frames. If you have a quality seller, the queen will have been in the hive for a long enough period of time so that she has laid it full of brood and all the bees in the hive are her daughters and are representative of her genetics.
A package will lose a significant portion of its population before a single new bee hatches. A nuc will have new bees hatching every day. It is already a fully functioning hive. It includes drawn comb.
Understand, I'm not hyping nucs because I sell them. I do, but that kind of idea is backwards. I sell nucs because I strongly believe they are the best option for starting new hives. Well, the best option is splitting your own, but if you need to buy some, nucs are the best option. And that's why I sell them. If I thought packages were the best option, I would sell them.
For a seller, packages are probably the best money making option. They cost very little in resources, essentially just bees in a screened box. And they tend to die about half the time in the hands of a new inexperienced beekeeper. So not only do you sell a cheap product for a significant chunk of money, your customers keep coming back because the product they bought keeps breaking.
Well, there you have my view. If you have any other questions, I am happy to answer them.