All the audio bootlegs in existence amount to about ~600GB at best, the rest is video. Let's say there are 10 Blu Ray recordings out there, those are another 200GB circa. The rest is all video bootlegs.
Let's say the average size of a DVD bootleg is 5GB (accounting for the both the double DVDs and the lighter ones), it gives around 1.2TB/5GB=240 DVDs circa. It's a rough estimate, but it shouldn't be too far from the truth.
Wait, it was 3TB, not 2TB. This makes the overall number of DVDs around 400. It's way too many, maybe I underestimated the overall audio share of the collection.