From each according to his ability, to each according to his need
You have to reflect on the contribution that gbpvr makes to your life and be comfortable that you have made a contribution that reflects the enjoyment that you receive from this software.
The way that I think about it is that if Sub ever pulled the plug on gbpvr, I want to to be comfortable that I had at least made what I consider to be a reasonable contribution to the project. I would hate to be in the situation where I was thinking "If only I had given more".
Sub does not want people to kill themselves over gbpvr. If you genuinely can't afford to pay anything, that's fine;enjoy the software. Those of us who have a few $ spare, should reflect on how we spent our money on the things that add value to our lives.
Only you can decide how much. I am sure Sub would rather receive $5, rather than nothing.
Silverstone LC17 Case,
ASUS P5Q, Intel E7200, 4GB RAM
Blackgold DVB-T2, ATI 7750, Windows 7 64-bit
SAF codec pack,Sony 40" Z5500