It appears from looking at the Smartthing site, there are no Z-wave bulbs listed as compatible that are less than $25. Why won’t Smartthing certify a bulb like the GoControl Z-wave bulbs to create an affordable option for Z-wave bulbs?
Most likely the generic device handler should work (if the bulb accepts generic commands… which any smart bulb should), but not sure how ST’s certification works exactly, it might be the manufacturer who needs to approach them.
The official list is just the tip of the iceberg… nearly any Zwave bulb will work unofficially with the default device handler.
I have a dirt cheap bulb in my loft that works perfectly.
There is also a new range from IKEA which is breaking the price range mould!