i would prefer if it is cheap because i would love to have one for my mini fire alarm system in my bedroom
They appear on ebay every now and then, but are super expensive. You might be able to find them cheaper on Facebook Marketplace or elsewhere. You can also ask around to see if any are being taken out of a building.
Yeah, & like I said in another topic they basically can’t actually do anything either (including anything more than what a simple pull-&-alarm setup can already).