Why are some seeds so much cheaper? Because plants produce a lot of seeds and some people have lower prices to sell more. That doesn't necessarily mean that the seeds are not good. Maybe the outfit you referenced isn't in to gouging their customers and is able to make a decent profit without bending people over a barrel and giving it to them in the backside. Some breeders actually breed while others just make seeds. Even some of the expensive seeds are just pollen chucks using obtained genetics. People can call their seeds any strain they want. It doesn't mean that they have anything to do with the original.
I think most seeds are extremely overpriced, over hyped, and put out by people just making seeds with no thought on any actual breeding. Try some of those inexpensive seeds and see what you end up with. You'll probably be surprised. $130 for a pack of 6 seeds is just stupid. I've never and never will pay that for a damn pot seed. I don't care how many people rave about them. I've grown some so called rave strains side by side with crosses I've made and genetics from some breeders that people talk trash about. My crosses and the so called inferior genetics produced as well or better grown under the same environment.
The cannabis industry is full of hype, misinformation, and shills pushing this product or that breeder. You can't believe anything you read or hear as as you don't know the motivation of the source or if their biased for one reason or another. Many push specific products because they get kickbacks in the form of free stuff while others have a business interest. Best thing you can do is try different genetics and see for yourself. I have and found that most strains don't live up to the hype and are not worth the $20 - $30 a seed people are paying. Chasing the latest strain because of something you read online is a fools errand.