Not very easy, unfortunately. In the last years there's been a steep price increase (both to rent and to buy), that's even worse in some areas - in Kreuzberg we've recently seen a listing for a 10sqm "apartment" for 750 euros/month, which is more than what you would pay for an apartment ten times bigger, just three years ago. Of course this is an outlier, and I believe they'll change the listing pretty soon, but that's the trend.
Prospective buyers don't fare that well either: from what I can see, the prices are now comparable to that of any other big european city (London and Paris excluded because those guys are crazy), at least in the most fashionable areas.
On the other hand, there's still a lot of "unexplored territory" where the prices are more than reasonable - a 3-room apartment for 250.000 euros or less - with the caveat that you're probably going to have to speak a lot more German than what you can get by on in Kreuzberg/Friedrichshain, and night life may be a bit tamer than what you would expect.
One final word of warning: renting is a lot more difficult than buying for several reasons, so expect anywhere from two weeks to two months to find a place (unless you're ok with overpriced dumps, of course).