If the gun was made by Jack Garner, who started TVM before selling to Matt Avance, the gun should be a well built gun in the style of traditional muzzleloaders. There may be a few inconsistencies, such as the use of a Siler lock (Germanic style) instead of an English style lock, a little too much wood in a couple of places, but all in all it should be a good gun. Be sure to inspect carefully for signs of abuse or neglect.
I know nothing of Gobbler Knob Longrifles.
Now then, there are many factors to consider with respect to buying used or having one custom made. A custom gun will be made to your requirements. You can select lock style, triggers, barrel length, caliber, rifling twist, length of pull and stock wood. Expect to be added to the builders backlog and wait for a couple of years to get your rifle.
A used gun, you will have in your hands as soon as money is exchanged. If you are selective in your seeking of a rifle, buying used could take some time too. Compromises may be made with respect to caliber, lock, barrel length furnishing material and length of pull. Being selective could also take some time.
