This one?

https://www.amazon.com/FieldSport-Micro-Sight-Precision-Green/dp/B00Y3SZEJC

I need one and would definitely be down to try a cheap one for only $20!

I've had this for years with no complaints.

FieldSport Micro Red Dot Sight, Precision Red Dot Only No Green https://www.amazon.com/dp/B00Y3SZEJC/ref=cm_sw_r_apan_glt_fabc_0E15C1HRYYK4G01MH9YC