Around here there use to be several video stores, now that the Red Box machines are all over the place that you can rent a new release movie for $1 every rental store has closed. Why buy a movie when you can rent it ten times and still only pay half the cost of buying it new?
I try to limit myself to $5 movies. Occasionally, I get lucky, like 20 westerns for $5 or 20 war movies for $5. At least a few are going to be worth the hour or two that each movie runs. I did break the rule for a boxed set of the 3 released Bourne movies - I think it was $24.95 for the set. Trying to clear out inventory before the Blu-Ray version came out, I suppose.
But if you are paying $20 for DVDs, you need to hit the bargain bins.