Kits
I would pose the question as to whether you are getting a kit to see if you like fly tying, or because you've decided to tie, and are committed to learning.
If you just want to test the waters so to speak, kits are fine. You'll be able to see if it's something you enjoy without spending much money.
On the other hand, if you've decided to take up fly tying and intend to make a serious effort, every kit I've ever seen leaves a lot to be desired. The makers shoot for attractive prices, and you get very low quality everything. If this is your direction, buy a good rotary vice as step one. Second, figure out (from past experience or by talking to someone in a fly shop) what fly patterns you will use most. Buy decent quality materials for those specific patterns, and then start tying. You will learn faster, produce higher quality flies, and keep yourself from forming bad habits due to poor equipment/materials.
In fly tying, as with many hobbies, I've found that buying the cheap all-in-one kit is usually not saving me money. Rather the $50 goes towards some throw away gear, which is soon replaced out of frustration.