When I first started getting in to building and doing my research, that research also included suppliers. By being on this forum any amount of time you quickly pick up who does what. Certain components come from certain suppliers and you just learn in it. The same with kits. I will use one example, for me the only real accurate Southern Mountain Rifle "kit" is the Jim Kibler kit. Now that being said you can also get a good quality parts set for a Gillespie Rifle from Dennis Glazener, but most would not consider those a "kit." So if it is an authentic Southern Mountain Rifle "kit" you seek, there you are.
To say Colonial Rifles opens up a bit bigger can of worms. Certainly you have the Kibler Colonial Kit and you have Jim Chambers as well. If it is a trade style gun you want, you go to Clay Smith. If you want a Colonial era Fowler then you are going to go to Jim Chambers Flintlocks or Clay Smith again.
I have built guns from Clay Smith Kits, Kibler Kits and Chambers Kit and can say they I really do not think the quality is that much different. The level of work you need to do may be different. I found that the Kibler kit was almost ready to finish. The Smith Kits and the Chambers Kits require some more fitting on all parts. (I have worked with other kits for other suppliers but would not recommend them)
My first build I had Dave Keck inlet a barrel for me, so if that is what you are the most intimidated by that can be taken care of.
I will say this. When I first started, what intimidated me the most was the metal work. Drilling holes, dovetails, shaping etc. I was most interested in the wood working, since that was my background. Most kits leave less word working to do, but all of the tricky drill of the metal parts.
Cory Joe