Depends how 'into' your ML your going to be. If it's just to enjoy the Dec hunt..then any of the $300-$500 ML Cabela's sell will fit the bill. They have good sales. Just pick an inline (removable plug). Most are 28" and will shoot 1" MOA at 100 yds right out of the box.
CVAs seem to be popular. don't hear to many bad things about them.
https://www.cabelas.ca/category/muzzleloaders/2542