Just bought my first house and dug this a few months ago one bored afternoon. DIY for $81 (cost for $80 pond liner & pump kit
+ $1 dish tray / washing bin from BigLots as waterfall / biomedia housing).
Weeds & clearance houseplants. I have no grass and don't water my yard, just drought-tolerant weeds that survived. Maintaining a lawn isn't very environmentally friendly imo--amount of water wasted & fertilizer/pest spray runoffs.
Various self-made wabikusas from tank plant clippings, plants in planters, and plants directly in pond dirt covering maybe 60% of the area, a few floater hyacinths. I threw about 2-3" of dirt from the yard into the pond. It sits under a couple trees so lots of leaves + pretty tannic, but zero feeding/maintenance. Shrimp & snail eat leaves; fish eat bugs and shrimp, etc.
Goldfish and platies, as well as a throng of shrimp