The flue size for the 130K btu units are 5", for the 260K btu units are 6" I have 6" connected to an 8" masonry chimney..
Both the AHS and AA 130 NEW are around $6000, you'd have to call to get accurate numbers.. I never buy new.. I bought my AA 260 off of ebay, and completely rebuilt it..
There is a long thread about my rebuild with lots of photos.. do a search on the forum for ' Axeman Anderson disection' I think that will bring it up.
There have been several AA 130 units come available used,, for less than half the price of new.. keep an eye on your craigslist, local papers,, and most important, contact your local heating installers.. they often remove perfectly good coal boilers, and SCRAP them [what a waste] when installing a new oil or gas boiler... contact them and tell them you will gladly remove and pay for the old boiler, more than scrap price.. Money talks..
Here is the rebuild 'disection' link: Axeman-Anderson Anthratube 260m disection