I am quite drawn to the Shimmels. Dixon's had a lovely one in .36 that I was very impressed by, but I'm a southpaw and I intend to hunt it. Colorado requires a .40 and Pennsy a .45 so.....I'm now looking.
for deer- personally i think a .45 is minimal anyway, the flinter I have taken most of my deer with uses a patched .490 ball
you won't find a better gun by nicer guy than Allen Martin but quality is not cheap and the good ones have waiting lists - no different than the good double gunsmiths
find a copy of Muzzleloader magazine - since it changed hands you can find it on some newstands or
http://www.muzzleloadermag.com/they highlight some good up and comers a few times a year and many makers advertise in there
you can find some examples of some makers' work here -
http://www.longrifle.com/or watch the for sales posts here -
http://americanlongrifles.org/forum/index.phpyou'll see a mix of used ones by known makers and some decent guns by good hobby makers