Recon Armor (Fallout 3)

The Recon Armor is a specialized suit issued to Capital Wasteland Brotherhood of Steel Initiates, and is basically the underarmor of the Capital Wasteland Brotherhood Power Armor. It is, essentially, a padded jumpsuit covering the entire body, integrated with the interface for the power armor. Unlike the underarmor for the T-51b models, this one is designed to offer limited protection.

Procurement
A fully repaired suit of Recon Armor can be acquired in Fallout 3 after you complete the Finding the Garden of Eden quest. Towards the end of the quest of The American Dream you will head to the Citadel. Follow the objective marker until you meet up with The Lyons' Pride. You will go into a HUD-less cinematic. During this cinematic, you will be asked about the G.E.C.K. When the conversations are over, you will speak to Sarah Lyons. She will offer you Power Armor or Recon Armor. You can also find suits of this armor in the lockers in the vaults.

The armor (although not full condition) can sometimes be purchased early from Karl in Meresti when attempting the Blood Ties quest.

Moira Brown in Megaton has also been seen selling this armor early-game (it seems to be random, and also likely that other merchants might have it).

The armor, along with the Recon Helmet, can also be found early on in an abandoned "Bait and Tackle" shop just north of the Citadel, across the river. It may also be purchaseable through Flak and Shrapnels shop in Rivet City - I found it there on my first run-through of the city.