No worries, make sure you really do your homework to know what your buying. My recommendation is to buy a full set which will make it more valuable down the road and easier to sell/trade if you ever decide. Since they are so hard to get from a AD (although not impossible) without a long relationship or spending large amounts of money a trusted seller here is your best bet.
Depending on what you decide on you may or may not spend over MSRP but you will have the comfort of knowing your getting the real deal without the potential of getting ripped off which seems to be running rampant on many forums with scammers.
Here's a few of the higher volume sellers here.
https://davidsw.com/
https://www.aiswatches.com/shop
https://www.ocwatchguy.com/
https://www.takuyawatches.com/watches/
https://www.sdwatches.com/
Best of luck in your search. The Sub is the quintessential Rolex.
