Greebo is pretty much right. If you're well known in the community, people will feel more comfortable trading with you. If you feel that constitutes discrimination, then fair enough, but I'd say it's true, on average.
As for rune values in "a vacuum", I think Ber is worth a bit more than Jah. If I got more than Ber for my Jah, I'd feel I was either getting lucky, or dealing with someone semi-desperate, or dealing with someone semi-ignorant of recent forum trends. Ber+Vex would feel like stealing. Others may (and will) have different opinions.