I bought 10 a few months ago of 0.010 uF for $50. Measure between 0.010 and 0.018 so I can use on neck and bridge. Some of them sound better than others within the group.
Are they worth $5 each? sure.
I wouldn't pay the $40/cap some of these eBayers are paying.
I think PIO caps can be a bit too warm for some guitars though.