How do you average Ki values?
Since I asked this question I found out what I was doing wrong in searching for Ki (i.e. I thought the Ki ID was the test ligand and hence I was searching for drugs the wrong way) values but also how, I think Goodman and Gilman got its Ki values. 

I think what they did was they searched for the hot ligand that gave the most consistent and numerous Ki values and took the average of the consistent Ki values (with an relative tolerance of ~100% between results). Additionally since I knew the data, as is stated in the page displayed above, was taken 30 June 2009 I was able to eliminate some sources that were probably not available on PDSP at the time. Using this I was able to get consistent averaged Ki values in the vast majority of cases (with like, at most a small handful of exceptions).