[charlie-83]

That's not bad compared to Bluetooth. Also, you will need FCC cert by law and probably some UL certs if you actually want to sell you product anywhere so you are already looking at 10s of thousands even if you choose ZigBee. I would love to live in a world where indie hardware can launch wireless products without huge cert cost but that's not the world we live in.

[randyrand]

Use a pre-certified module and do your own unintentional emitter testing. It's not that hard.

You don't need UL for smart home sensors.

[charlie-83]

I don't think you can do you own testing like you suggest. You can self declare but you still need to include test data in that declaration so unless you happen to own all of the highly expensive calibrated test equipment you will need to pay an external test lab.

You don't need UL if you are just selling directly via your own website. However, if you want to sell the product in stores, most stores are going to require it.