Let us first clarify a few definitions...
- Light (at the subject) can be 'direct' or 'indirect'.
- Light (at the subject) can come from a 'small source' or from a 'large source'
- A modifier makes a very small source into a 'insignificantly larger' source, or into a 'appreciably larger' source
- A softbox is a 'somewhat larger direct source'
- A reflective umbrella is a 'somewhat larger indirect source'
- A transmissive umbrella is a 'somewhat larger direct source' and can also serve (via the spill off walls and ceiling) as an 'appreciably larger indirect source'
- Ceiling bounce generally results in 'appreciably larger indirect source'
- A Stoffen is a 'insignificantly larger DIRECT source' which also serves to turn the ceiling into a 'appreciably larger indirect source'.
- A Lumiquest 80/20 is a 'somewhat larger DIRECT source' which also serves to turn the ceiling into a 'appreciably larger indirect source'.
When there is no ceiling or nearby walls, indirect (bounce) is useless and unavailable -- unless you are bouncing from an umbrella or other reflective panel. But that is the same as the effect you get from a direct source of the same area (large softbox).
There are lots of debates about what makes a 'cost effective' solution. Some solutions are very cost effective, but there are times in which they are USELESS too, when the cost is infinitely high compared to the effect they provide.
Any and all of the above can be used at the camera, and/or they all can be used for OCF.