Hello Paul, and welcome!
If you haven’t already I would check out the docs LowRider CNC V3 - V1 Engineering Documentation
That will give you a real good idea of what is involved in the build and you might see a few things along the way you haven’t thought about yet.
One Suggestion I would make is go for the Jackpot controller. Its a lot cheaper than the SKR and I personally like running the machine that way better. All of mine originally had SKR boards and I have since switched them out to Jackpot boards!
If you go to the jackpot board then you wont need the addon screen box for the printed parts.
Do you already have the Kobalt Router? If not you might want to make sure you can get your hands on one before you pick that tool mount. They were tested by Lowes but Kobalt decided to discontinue. If you can get one that’s great, if not then I would go for the Makita, and pick up the 1/8" collet from the V1 store.
Other than that it looks like you are pretty much covered for parts that I can tell. Someone will come along and double check me 
You will need some other things such as a table of some sort to run the machine on (Ryan has a parametric table that you can cut with the LR on the ground and put together) and you will also use the LR to cut its own struts out.
Might pick up a few extra endmills. Learning can take their tole on them (I speak from vast experience here)