Yeah, even here in the US DVD's are expensive, and I know that outside they are even more expensive. As for me, I really don't buy series on DVD's, only movies, or series of OAV's, but not TV series. I have quite a bunch of recorded chapters of Dragon Ball Z and some few of DBGT (which I hate to the heart excepting the end)
I actually buy between 1 to 3 DVD's per month. But I have not been doing that for long. The first DVD's I bought were the Rurouni Kenshin OAV's 1 and 2, (Samurai X, Trust, and Betrayal). Later on, after about 3 months, I bought Vampire Hunter D: Bloodlust, a month later I bought Bastard!! (complete collection of 6 OAV's in one DVD) and 2 weeks ago I bought the first volume of Street Fighter II V from a set of 4, and probably tomorrow I'll buy the second volume.
But you know what, I just go to a share network and download all the anime I want
By doing that I have watched about 20 different animes, I think. What I've done, is to watch them first, and if I like them, then I buy them on DVD, which is what I am doing right now.