For a low budget independent film I thought Open Water was well done. It was filmed over a two year period on weekends by a husband and wife production company. The actors had to commit to that time frame due to the couple working a week day job.
I don't remember the cost but it wasn't much. Most of the cost was traveling back and forth to the shooting location. The camera equipment wasn't very sophisticated from the documentary I watched and they edited it themselves on PCs with Adobe Premiere or a reasonable facsimile.
I can see the help wanted ad for the actors in an issue of Variety.
Do you like weekends in the Bahamas? Are you SCUBA certified? Can you commit to a two year production schedule? Do sharks scare you?