My experience, should it help: I had assorted CA munis. All varying maturities and sizes, but most longer term (10y – 20y). I sold off 75% in late 2007, and the remainder (odd lots, about $10K chunks) in early 2009. I used Schwab’s bond desk. Supposedly they contacted bond dealers throughout and asked for bids; I did not ask how many dealers, and which ones. My impression was that the larger chunks ($50K) got better bids, at least relative to the recent pricing noted by Schwab. The basic lesson I learned – this was my first venture into direct bond ownership – was that buying small bonds is sort of okay, though you will get a few basis points yield better beginning at about $100K, but selling small bonds is a pretty bad experience. My advice would be to call various brokers and ask at their bond desk what they could do for you and what they would recommend. If you are looking at an assortment of small bonds, you may be out of luck.
There are also muni bond dealers who post their ask prices on the web.