Where to find, or on which level is Secret Service armour available?
I suppose you could get it at any level, but waiting for level 50 seems wise. In my case level 130 or thereabouts. Secret Service armor must be purchased with bullion, or the plans must be, to be precise. So you need to do the vault 79 quest to open up the bullion economy, then accrue enough bullion to buy the plans. So this is a long-haul objective. It's at the end of the Wastelanders quest line. You can get the stealth armor a lot earlier in this line.
There are a number of ways to get bullion, but the main way is participating in events and getting treasury notes as a reward. These can be redeemed at gold machines for the bullion. There is a ton of amazing kit available through the bullion vendors.
To achieve anything in this game you must be prepared to dabble in the boundary of disaster — Stirling Moss
