Agreed.
I can get a 4-string set of SIT Power Wound Nickels or GHS Bassics for $18. Are Stringjoy good strings? Maybe... Are they worth $30? Probably not...
It depends on one's perspective.
I'd say that SIT nickels are way underpriced for what they are, which is a top shelf string IMO. GHS Bassics are fine but much lower on my personal totem pole.
To me Stringjoys are worth it because I was able to order them in a custom gauge and their longevity is outstanding in my experience. Obviously I like their sound and feel as well.
My $0.02 only...