Andrew,
While it is true that "a sucker is born every minute", that saying applied to these companies may not reflect the true state of affairs. It implies they're charging higher prices just to rip off people. They may just not be able to buy in large enough quantities to get the discounts that Buddies and other get. So they may not be able to offer the low prices. (Buddies also offers absolutely incredible customer service, as many have learned.)
Internet businesses are very attractive for many reasons and many people have started them in hopes of achieving the "American Dream" of financial independence. They can stay in business because not everyone can find every great place for buying what they want. For instance, I never heard of "Bowling Sphere" previous to your mentioning it, but I have a list of 20 or so internet bowling supply places.
Of course, while the above is true, it does not mean that some of these places are not trying to make more on each individual sale than other places are. They each have their own overheads and their own decision making processes.
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"We get old too fast, and too late, smart."