Like... A dress uniform???
I'm pretty sure since they're Navy they wear standard navy dress.
Try here: http://www.tridentmilitary.com/
I know they sell Chinese PLA dress uniforms so they might also sell Navy uniforms.
Also if by shoes you mean dress shoes I believe officers use oxfords (well... at least here anyways). Might also use oxfords in the US Navy.
If you mean "combat boots" then I'd try to find the model of boot they use and see if you can get them from a surplus store or something. I know that you can get GSG9 boots off the internet so chances are you're likely to be able to find the Navy SEAL boots somewhere.
EDIT: Did some searching and here's dress uniforms if that's what you're looking for. http://www.tridentmilitary.com/us-mi...usm-index.html
and combat boots mostly from Europe though: http://www.tridentmilitary.com/Boots.htm