@TheRealMulli Welcome to the Braver family!! We apologize for the price of katanas on the market 
When it comes to builds, Ahri's Braver guide has links to popular ones for katana Braver and I'd also recommend checking out the 2nd post on this thread (by AndrlCh). If you wanna lean more into Bows, there's a beefy guide by Argus and this recent Reddit post summarizes that plus gives a link to the full guide. I also hear that the fleet discord channel has a lot of build guides, but discord is beyond me 
Once you get to Lvl 90 decision making becomes easier because you can take almost everything you want on both trees, so it's probably more useful to talk about the order of progression:
I roughly followed Ahri's suggested order on the Braver tree which is: Katana Focus > Basic Stance > Basic S Up > Basic S Charge > Katana Combat > Combat Finish > Combat P.Attack Bonus > Combat Escape > Enhanced Attack > Katana Focus Boost > Counter Edge > Counter Bonus > Precision Stance > Precision Stance Up > Precision Stance Charge > High Level Braver Bonus > Perfect Recovery Heal Level 1 > Quick Mate >Sidestep Tackle > Perfect Recovery Heal Lv. 5
And then on the Hunter side he recommends: JA Bonus 1 -> Fury Stance (Max) -> Fury S Up 1 -> Fury S Up 2 -> Ja Bonus 1 (remaning points) -> Ja Bonus 2 -> Fury Combo Up -> Healing Guard -> Guard Stance (3) -> Automate Halfline (max) -> various other options depending on playstyle (iron will, Hunter's Physique, etc.). "JA" stands for Just Attack, but on the global servers it's called perfect attack.
As for general Braver tips, I'd recommend watching some of these videos. I also left some food-for-thought regarding weapon progression in this thread. There's much more we could talk about, but so long as you have your Mag and Skill Tree set the rest you can learn along the way. So please come back and post questions as you progress on your journey to become the bravest ARK there ever was 