Mon cher Amir,
Yes, "assuming".
But here are some facts. ...DVDs; people (I included) paid on average $25 each! ...Some cost $60, others $10. ...And when people started (I included) back in 1996-97 to purchase them, most of them were $25-30 (and even more with tax). ...In North America (Canada), and also in the U.S.A., and also in the U.K.
Blu-rays (I stop buying DVDs in around 2008, and started buying HD DVDs in 2006-07); they cost on average (since 2006-07) roughly $25-35 each.
Some Special Editions cost more than a hundred bucks, and nowadays, for titles that are from the prehistoric age you can get for five bucks each (not my style).
Criterions are $40-50 each, here in Canada. In the USA they are $25-40 each.
Disney BD titles are $30-35 each (2D), and $35-45 each (3D). ..Here in Canada you have to add 12% on top of that for the GST tax!
FOX, Universal, Warner Bros, Paramount, Lionsgate, Columbia (Sony), Alliance Films, Touchstone and all those other Disney's derivatives, and all the other studios from all over; for their BD special editions you can 'realistically' expect to pay between $25 and $40 each.
Now, I personally know (I included) people who purchase DVDs and Blu-rays exactly as described above. ...And not just one title per week, but sometimes dozens!
* That 6,000+ DVDs and Blu-rays is now realistically estimated at $150,000 very fairly (actual cost at the time).
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This is nothing! ...Other people have movies' collection (Laser Discs, DVDs, Blu-rays) with over 20,000 titles, and even 30,000+ different titles.
Some of these people buy all the Special Editions of those video formats; no matter the cost.
Now we're talking! ...Huge amount of money, a big pile (mountain) of it!
And those movie titles are not on their walls, but they have a room (big big room) strictly dedicated to them (of course, that's the only way).
Eventually I'll post some of the best of them, so stay tuned. :b
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VHS movies; let's not go there; I spent a fortune in the old days.