Just go straight to Dillon. Its going to be about the same price anywhere unless you buy used. BTW I have my Dillon 550 for about four years now and love it. Its the only way to go for me. YMMV as always.
Go through Brian Enos and he pays the shipping (on orders over $400 and a new 550 press will be over $400). Go straight to Dillon and you pay the shipping. You get the same product at the same price from the same place either way.