It is important to be sure that the prices you're paying for websites and blogs are reasonable, of course, just like any other market. It is also essential that you make sure the company or individual selling the web site goes through the proper registration channels and everything.
You can find literally an incredible number of blogs and websites out there. THey really suck sometimes. Most of them fly beneath the radar getting only a few hits each month, or even less. Many of them are just empty husks waiting to be used. Many more have such complex domain names that they'll never be utilized in anything significant. The way forward for the online world is far from clear--but this much seems evident, the selling and buying of blogs and websites is only going to become more significant as an industry as time passes. Totally poor.