But are they really that outragious? You aren't making any money from this excercise so there is a lot of work going unpaid (by you and the people who have volunteered to pack) which means that it's unfair to compare the price you've arranged with the price that a retailer will charge.
A retailer has to factor their overheads (insurance, rent, wages, etc.) into the price of the goods they sell. So there is justification for $90+ per kilo because that $90+ per kilo covers all those overheads which you don't have.
$20 per kilo is only possible if you are able to continue to do this for free. If you need to start behaving like a retailer (i.e. having storage space, paying for the packing, offering shipping) and adding a little bit extra for the time you've spent, I'm sure that $20 will start to climb.
Andrew