Well... I'll differ by not suggesting the quite "exotic" stones listed in the thread. If you're starting out, I think you can't go wrong with the classic Norton 4k/8k to get an edge back... then, if you don't mind throwing a bit more to get an higher grit polishing stone... the "chinese 12k" is the best value there is. They don't get talked about much here anymore. These 2 (well... 3) stones will cost you maybe 10-15$ more than a single nani 12k will.

Also, I recently discovered the DMT goodness, in the D8EE... "cuts like a 4k, polishes like a 8k" holds true. It has quite a few advantages over the Norton... no lapping, no soaking, no pyramid honing.

For a bit more, a two sided BBW/coticule is a very good buy too and will/may give you the smoothest edge over all of these, depending on which ones you will find.