My experience with that style of circulars has been terrible. The bamboo needle part is inserted into the plastic tubing (which is very stiff and kinks instead of bending) and that with any stress, they pull out of it. I don't know about their straight and dpns, though I did get a very similar looking set from eBay and ended up with bugs in the packets. And I would not be thrilled with a company which lists 15 circular needles as "30 count". No one counts each needle tip as "1"
Maybe I'm too suspicious, but the prices are a little suspect as far as I'm concerned. For a complete set of DPNs, 15 sizes, 5 needles in each size, they charge $30. With free shipping. So let's say that's $5, which means the price is really $25. That means that each set is $1.67. So that means they paid maybe $1 for each set of 5, which is 20 cents per needle. That sounds as if the quality of the wood or workmanship is going to be pretty bad. Or they're using 8 year olds in a 3rd world country to manufacture these things?. . .I don't know, but I'd steer clear.
Here's something to remember-- knitting needles do not go bad. Spending some extra money is a good investment in the long run. A set of Harmony circs is $75, as opposed to $30 from the other. We're talking a difference of $45, not $450, and over years and years of use, that comes to a few pennies per month. I'd go for it!