The google link command is worthless. PR can be faked. Do a search for "www.domain.com" with quotes. That shows you more links. The best thing to tell is see what it ranks for. Look at the home page and blog home page title. Try differnt searches using the words in their title. If it is not number one for its title then it is not worth much. Unless they just have one or two words in the title. Look at the age. The older the better. Also bloggers are funny. If you don't keep the site the way it is they may take down their links. It is always a good idea to study the links. Decide what the risk is of losing them. If you see any red flags don't do it. I have purchased many sites and have never been burned by following these rules.