I am firmly in the camp of buy tools as you go. In the end 3-5K in tools is not unreasonable to plan for, but it can be spread out over years rather than all up front. $1,500 up front should get you what is needed to start.
I used the kit contents to get an idea of what I would need, but found many alternatives that I liked better. To be specific on a few alternatives, one tungsten bucking bar is worth a pile of steel ones. Not to say you won’t need many steel bucking bars. There are so many rivets that are hard to get to that you will need to get very creative with bucking bars any way. I have made at least 6 from scrap steel and an angle grinder. And buy a 3X rivet gun. A 2X is on the small size for the AN-4 rivets. (If you can buy 2 guns a 2X is lighter and easier to control so buy a 2X and a 3X.)
I have an air and two battery drills. Most times you will need several bits in sequence. It is nice to just switch drills rather than constantly switching bits. And I use the battery drills for tons of chores around the house. I almost never drive a screw by hand. You will also need a bigger drill than an air drill for some of the holes in the steel components (at least on the RV-10)
The DRD2 is very much worth the price. While a C-frame will do the job, sooner or later, after dimpling hundreds of holes, you will lose focus, or the piece will slip and punch a hole in the wrong place. While the DRD2 can do the same, (I prefer not to be swinging a hammer at my project) you can ‘set’ the upper and lower dies lightly in place in the hole before bearing down to make the dimple. Noise may also be an issue in your work area, DRD2 = quiet, C-frame = lotta banging going on.
For a squeezer, I bought both a pneumatic and a hand squeezer. I never used the pneumatic squeezer. I found anything with in the depth capability of the hand squeezer was quicker without the need to set up the much heavier pneumatic squeezer and awkward air hose etc. I would recommend the ATS Pro squeezer https://www.aircraft-tool.com/shop/d...spx?id=5011-1A
with the bench mount kit. The bench mount kit frees up the hands to hold the small parts. That is worth a great deal of frustration mitigation.
For the power tools, bench top drill press and band saw are plenty. Even a small compressor will drive a rivet gun and drill. They are very noisy, so plan a location remote from family and work station if possible. For that a portable that you can put outside while working is a good solution if the neighbors aren’t too close. One of my real ‘go to’ tools is a HF 12” disk sander. I use it so shape and clean up the edges for the many cut out parts. I don’t like files and rarely use them where the sander will do the job in seconds with much effort. I wouldn’t be without it!
For deburring I have several unusual favorites. I use the 2” scotchbrite wheels on a small angle air grinder. Much easier to bring the grinder to the part than the part to a larger stationary grinder. I have worn our 6 or 7 during the RV-10 build. The Speed Deburr tool https://www.aircraft-tool.com/shop/d...aspx?id=AE1046
is indispensable. I even use it to do quick countersinks when there a just a few and setting up a cage is just too much trouble. (By the way, multiple cages at least for each size is a great recommendation) I also spent the money for the Two-way deburring tool https://www.aircraft-tool.com/shop/detail.aspx?id=TD001
for deburring skins. It is expensive, but saved hours of tedious deburring.
Lastly, buy lots of clecos. A few hundred to start, but add hundreds more as you go.
Much more to say, but this is already too long. I short start easy with just the basics, then add as you go. Building a plane is a marathon, not a sprint.