They don't publish the monthly or bi-monthly books anymore; they do however make annuals and I also believe they publish a quarterly. Monthly updates are in the Baseball magazine I think. I know because I bought an annual about 4 or 5 months ago from a local dealer.
i just went to beckett site, and i guess they still make the bi-monthy issues. from the looks of it, you can only buy them from the web site. i haven't seen an issue in a store for a long time. http://www.beckett.com/beckettracing/default.osi