Well, you have to consider that deputy services
are not just a japanese address to have your items
sent to. Deputies handle all the communication
with the seller, check if/when the item arrives
and even provide storage space for your items
until you have enough to be sent to you, and then
packaging everything together to be sent to you.
All that has a cost and definately saves you a lot
of work.

Anyway, if you want to deal by yourself with
sellers that ship internationally you can just ask
in this forum as for sure several people will be
able to guide you about creating your own YJ account.