I think products to use such as shampoo and such are a personal preference thing and what agrees with your horses coat and skin...some products cause issues for some animals and not others.
I don't use hoof oils anymore...beauty and gleam come from good nutrition and many things you paint on actually dry out or hinder the hooves ability to breathe and absorb/shed moisture as the elements demand and need.
I started out with simple brushes to clean my horses... A soft brush, a hard or mud brush, hoofpick brush combo, a sweat scraper. I bought a car wash sponge and bucket from Walmart for washing the horse.
To this day my brushes cost me less than $10 per and do a fine job. I can see some having great fun spending 3x that amount for 1 brush but I truly don't see the point in spending oodles...clean is clean when you know how to apply elbow grease appropriately.
This is honestly where I buy much of my equipment as it is affordable, entry level quality that gives years of service without breaking the bank financially. https://www.chicksaddlery.com/horse-grooming-aids
From halters and shanks, brushes, saddle pads and honestly some of the saddles are not bad either...I've had lessons sitting in some of those saddles many years ago and they were safe, comfortable and assisted you with position proper for a realistic price paid.
Other places I've spent much time looking at and many dollars purchasing from is https://www.statelinetack.com/
Great places to find value and approximate costs of items for reference before spending to much or knowing when to spend now for a great deal..
Neither of these places offer top of the line but you don't need that honestly, you need everyday serviceable quality to start your adventure with...you have years to upgrade and get into the fad items that cost so much.
I don't do "treats" as in buy them, I don't.
Our horses will get apple cores when I'm done snacking on a apple if trail riding, sliced apple or carrot but I don't buy cookies or packaged treats...just don't spend my money that way.
Once in a while a alfalfa cube broke into thin slivers as my one horse has choked and not going down that path ever again I hope...otherwise, no commercial or bought treats.
So, the one thing I will say you must
have is a secure locking trunk/cabinet large enough to store your barn needs in.
For now something like a foot locker you can get in Target, Big Lots will work to get you started.
Be careful of the quality some of those cheapies are cause if in a barn it does take some abuse and banged around just cause it happens so make your purchase stronger than bottom of the barrel cheap but not costing...crazy!
I've seen some nice stuff come from Home Depot too...do look around.
Depending upon barn security for tack, bring your saddle back & forth in the car/truck daily.
Eventually though most expand their collection of acquired stuff and need more space and with more space needed so does the appearance of said product equally improve and get fancy.
Pinterest has hundreds of choices of "to make" designs and after looking at and drooling over the fancy you get a feeling for what you want yourself.
My husband made me some gorgeous huge trunks, free-standing for a fraction of what places sell already constructed/made for. I sold mine when no longer had horses where we previously lived, and even today at my home they would be unnecessary as no one steals so no need to keep under lock and key...
At my home I have plastic Rubbermaid totes with snap on lids that stack with blankets and sheets neatly stored inside. Another tote holds saddle pads... I write with sharpie markers on the sides what is contained inside.
I have other totes with excess, to much excess
as I'm hoarder and seldom throw anything horsey away if not "junk"
I found in a pawn shop for $20 a trunk like the first picture below, it is one of the really top quality expensive ones the horse racing and English riding elite barns require all students to have and match...
These examples below I found on Dover's website www.doversaddlery.com
The second one is affordable and looks sturdy enough to hold plenty and secure so no roving fingers help themselves to your things...
The first one is gorgeous but not
so affordable for many.
I've seen some nice trunks from Home Depot too...all with locking abilities.
When you figure out by seeing some others and examples around making your own is fun to design and personalize. Pinterest and Etsy have thousands of blueprints and ideas along with the pieces you need to finish them to very handy to have, can't find it anywhere hardware items.
We all start someplace and over time increase in amount what we have and then need to store so we get inventive and "wanting"...
Start though with what you need now, is in the budget and can safely keep your items clean, together and safe...then dream and fill those dreams in years to come.