Happy upcoming birthday!
I am a relatively new home-brewer myself, although I started out brewing 5 gallon extract kits using a 5 gallon kettle that I purchased in a starter kit.
The reason why I mention this, is that it wasn't too long before I started to look for a 15 gallon kettle so that I could start with all-grain BIAB (Brew In A Bag) brews. In hindsight, I wish that I would have just purchased the bigger kettle in the first place...
In any case, the Go Pro Small Batch Starter Kit includes most everything that you need, and you would be able to re-use most everything if you started brewing bigger patches, with the exception of the Little Big Mouth Bubbler.
You might want to consider picking up some Star-San so that you can sanitize your airlock, bubbler, siphon, tubing, bottle caps, and anything else that needs to be sanitized.
I was going to suggest that you pick up some sort of beer thief, a hydrometer and test jar, so that you could check the original gravity (OG) and final gravity (FG), but then I remembered that when you are brewing small batches you will end up using a good percentage of your brew for testing, unless you dump it back into the fermenter.