New double action .22 revolvers tend to be pricey.
You might be able to find something used in the S&W K-22 family for around $400 but it wouldn't be pretty.
Taurus has a couple of .22s but quality is a crap shoot.
Ruger has a .22 version of the SP-101. So far it has good reviews here on the forum. I haven't seen one in person. It's new so it might be hard to find.
H&R is a popular .22 in the used market. They're well made and still relatively cheap.
Single actions tend to be less expensive. Another thing to consider is that SA revolvers are real simple machines so a used gun is very likely to still shoot well.
The Ruger single six is a real nice gun.
I use a Ruger MK II as a trail/hiking/camping gun. Never felt the need for a centerfire.
If you decide on centerfire then look for a used S&W K-frame in the used market.