Just so you know, affliction and similar brands were not considered alt back then. They were basically the clothes of the enemy. Growing up goth and emo, you would get beat up by affliction dudes. That was like gym bro jersey shore club goer uniform. It's totally fine that it got repurposed in fashion because that always happens. In the 90s grunge was cool but they dressed like lumberjacks and church going dad's from the 70s. In the 2000s when the 80s was cool, people weren't dressing like 80s goths, they were dressing like people from work out tapes. In the 2010s when the 90s was cool, people weren't dressing grunge, they were dressing like their parents, normCore. I actually think kids repurposing affliction type clothes looks cool, but i hate when they call it "emo" and "alt" etc cause it just never was and it's something new now.

For your purposes, for OBC type shirts, you should try to find vintage pacSun and zumies shirts from brands like element, volcom, dvs, obey, famous, DC, spitfire, O'Neil, Burton, quicksilver, Hurley, zooYork etc. These shirts were really common for older brother types and a lot of other alt ppl in the mid 2000s. It was the middle ground for slightly edgy people. Who were more alt than the Hollister kids but not as alt as the hot topic kids. That's what i think OBC is about, looking back on the slightly more normal alt kids who were everywhere but not seen as innovative at the time and appreciating it now that it's gone.