My first guess: Nowhere.
No one makes pouches like that. It's a terrible system.
Things like mag pouches are bulky and, once filled, heavy. They swing and catch on things. Velcro will tear right off without clips, straps, or other more reliable mounting methods to back them up.
There's a reason UTG vests, even all decked out to the nines, only cost about $30.
They're fine for airsoft, paintball, and playing dress-up, but even most airsoft crap is just cheaper, Chinese versions of actual military/LEO service gear.
Cheap PALS/MOLLE gear is still going to hold better than just a Velcro patch system. The only time a Velcro-only system is sufficient is when it's a concealed system inside an enclosed bag. Maxpedition's universal concealment holster, for example, is designed to attach to Velcro pads inside certain portions of many of their packs and bags, allowing an easily accessed firearm for when on-the-body concealment might be less effective.