There's a 101A and 101B which has a few versions. There was a white chassis 101B with assignable outputs and a few other bells & whistles- some people love this version, some hate it. I had one but sold it. In 2004 the red channel of 101B was re-voiced for more gain (rumor is that Rheinhold never liked this mod). I highly recommend getting the Marvel mod. Switchable mod for the red channel that gives you pre 2004, post 2004 and Cameron mod. And then there's the 20th Anniversary XTC. I think that's about it. Check their web site or http://bognerampforum.informe.com/index.php for more info.
100a and 100b the first xtc's sell for 3000.00 to 3800.00
101 and b early ones had white chassis like 100 series. most of these have the cab switching feature which sucks tone according to many including reinhold. about 2300.00
101 and b with black chassis. these sell for about 2200.00 to2400.00 ... 2500.00 tops depending on current supply and demand and options such as metal grille and a/b option
101 series revised about 2004. These had more gain on the red channel and seemingly more gain on the blue too to me. alot of people like these. I found it to be more brittle and less creamy than the earlier 101b and the go for about 2300 to 2500.00 as a rule no more..
XTC Classic . close facsimile to a reissue of the 100b. therse go for about 2400.00 to 2800.00 although the market seems soft on these now because of the aniversary model so 2800.00 is long shot. I would pay 2500.00
xtc 20th anniversary. the newest xtc similar in layout to the Classic and 100b but reworked in may ways. some feel it is the best XTC ever. havent played one so I dont know. used market 3000.00 to 3400.00
There ya have it from the guy who has probably has bought and sold more Bogners than anyone other than maybe their top dealers...