The web is loaded with cheap high-volume pumps for ponds and many
things.

Well, I have that. What I don't have is a pump for my new project: a
small bog garden.
I want a pump with delivery measured in gallons (just a few) per day,
not gallons per minute or hour.

The best I can come up with is very specialized "metering" pumps that
cost several hundred dollars.
I realize there isn't much call for this sort of thing, but it seems
like somebody somewhere
has such an animal.

2 gallons per day at a head of 5 to 10 feet would be lovely. I just
want to keep the dirt wet.
No waterfalls. No splashes.

Anybody got any hints on this?

Hayden