Not much luck finding a cheap one. We had one ages ago from the reject shop, they don’t seem to sell them anymore.
$3 one on eBay but it’s a tube so not simple to attach to a fence.
Not keen on paying $10 for a simple bit of plastic, are there any cheap ones around?
You get what you pay for. $10 isn’t a lot more than $3.
You want cheap, make one yourself. https://www.education.com/science-fair/article/DIY-rain-gaug…
Go past Bunnings my local store usually has different ones on clearance for a few dollars. They are plastic but work fine and some come with ground stakes.
Curios Planet 40% to 60% off store wide - buy in-store only
https://www.aliexpress.com/af/rain-guage.html?SearchText=rai…