In order to get this achievement there's a simple strategy to complete this quickly and pretty passively.
1. Make two corrals with the high wall, air net, auto feeder, and plort collector upgrades.
2. Fill both corrals with 10-15 largos. Preferably late game slimes like quantum/crystal and
dervish/mosaic largos.
3. Use their favorite foods to gather twice as many plorts. All favorite foods can be found in
the slimepedia. The favorite food of either half of the largo will give twice the plorts for both
halves of the largo.
4. Harvest to your hearts content! If you let the four plort collector slots fill to 80 or so you can
very easily get 5,000 newbucks in a day.
Here's my video for every achievement if you'd prefer. Skip to 4:27 for A Quick Newbuck.
Happy Hunting!