I have several hundred DVDs. But, I digitize them, store them on a terabyte harddrive, and transmit them to the TV with an AppleTV. We can pack away the DVDs, and watch any DVD we own at the push of a button on a remote control. Saves space, and effort.
As for DVD purchasing -- I've found that pawn shops are a great place to buy ... $2-$4 per DVD, and you can find pretty much anything. I won't pirate anything, so I insist on owning a DVD of everything on my terabyte. My DVD collection has probably doubled in the past year, and I haven't spent more than a few hundred bucks doing so.
I don't do rentals or NetFlix anymore because I'd rather spend $3 to buy the thing than a one-time or monthly fee to rent it.
SnakeDoc