I charge $9.70 for under 500g nowadays, and that's not even covering all costs. A buyer recently complained (after buying, of course) that she could get my $20 item for $7 where she lived.

Physically restraining myself from pointing out that she should have got it where she lived in the first place and not bothered me, I replied with:

Australia Post - $8.30, ebay commission on postage - $0.83, ebay commission on the rest - $1.17, PayPal transaction fee - $0.30, PayPal commission $0.70, box - $0.80, packing tape & material & fuel to post office - $0.90. Yeah, $7 is about right. You have a good local seller.