It depends on which controller you mean and which region you are in (america and canada tend to run out of stock faster than europe and asia).
Quest 2 controllers are available as Tom linked above.
Quest 1, Rift CV1 and Rift-S controllers are no longer available.
(Rift-S and Quest 1 are compatible with each other's controllers. Rift CV1, Quest 1 and Quest 2 controllers aren't compatible with any other model of headset. For example Quest 2 controllers only work with a Quest 2)
The Rift-S is discontinued and the Quest 1 is probably being swept under the rug to not distract from the Quest 2.
Right now no region has Rift-S/Quest 1 controllers, which didn't happen to the CV1 until it was completely discontinued and all stock drained. Until then there were always some (maybe just left controllers, the right ones sold faster) in europe long after America ran out.
But there's always a chance Oculus will resume manufacturing. I doubt it though.
Most likely they've learned from the CV1 and Oculus has stock piled the remaining controllers for a couple of years of warranty replacements, rather than allowing people to buy up the last of the stock as backups they might not need.
On the positive side, the CV1 remote is still for sale. 🙂
@kojack I'm pretty sure the original poster was after Q2 controllers so these should be available for some time to come. Sometimes in/out of stock but restocked fairly frequently. Since all Q2's are still under warranty anyone with a broken controller should initially contact Oculus Support and start a ticket. Even if the person banged theirs up Oculus is often pretty generous about suppling replacements.
As far as Rift S and Q1 controllers go. If these are broken and still under warranty then obviously persons should contact Oculus Support and start a ticket. If they are out of warranty I think that they should still contact Oculus Support and hopefully they will be able to accommodate them, maybe using warranty stock.
You make a good point about people buying up stock they will probably never need. I know I've been guilty of do this on occasion in the past. Cheers mate.