Member Access Only - Allowing only those with an account to access store page

Hey there,

I've today purchased a subscription to wpmudev and so far, so good...

My store is wholesale to approved customers only. So, I want people to click 'Store' on the navbar and be greeted with a login page for approved customers, and a little message inviting non customers to contact us to apply for an account.

Once logged in, they then see the standard domain/store/ setup.

So my question is whether this is possible and if so, I would really appreciate any guidance on how best to set this up.

Thank you.