I've used the clear acrylic interchangeables (Zephyr's) that Knit Picks used to sell. I didn't purchase the whole shamoley, just three sizes of tips...6, 7, 8. They were very nice, but not any better than the wood Harmony's. A few tips had to be replaced because the stalk came loose from the ferrule. They didn't pop out, but they swiveled around, but weren't supposed to. I think the glue came loose.
That set you spotted on Amazon is a FANTASTIC price, and I personally love the colors! Nice compact zippered case!
Knitter's Pride has a nice good reputation. I've never heard anything negative about them.
But if you're making your purchase via Amazon, will you still have a reasonable manufacturers warranty, at least upon delivery for defects like what I mentioned?
For $31, how can you go wrong?