For years my wife and I have had an agreement. If one of us goes to the store for anything we pick up one of the items on our list to add to the preps. All of our items cost under $2 and will be almost impossible to get in the event of a serious SHTF scenario. Buying them a little at a time when you are already there barely even seems like you are spending money. Larger items and bulk food are mostly taken care of,as is water. I would like to know what you guys would  put on this list that I've not thought of,because eventually I am going to have enough of this stuff! My list is:

3 pack of ivory bar soap
4 pack of store brand TP
1lb of salt
1lb of pinto beans
16 oz alcohol or peroxide
Gallon of bleach
Store brand spice and gravy mix packets
Toothbrush
Qtips
Baking soda
2 cans of store brand veggies

What's your suggestions??

More 1st aid? You can get a box of bandaids or gauze for less than that.  Nothing else off the top of my head but I love the idea and once my house is done being built I think me and the wife may do the same

.22 LR at less than $0.045, buy as much as we can afford.

I also have a running list of tools/small parts I try to add one or two every trip to the hardware store.

Even after you cover most of your primary basics, start keeping track of the items used a lot because of convenience and assess their value.

You mentioned baking soda, that's one I've found using more than I expected.

Aluminum foil
Ziploc bags
Apple cider vinegar and white vinegar
Favorite spices
Olive oil
Hand/body lotion (my wife)
Hand sanitizer
Disinfectants and cleaners (bleach, Pinsol, etc.)
Basic tarps (different sizes)
Plastic sheeting/drop cloth
Duct tape
Coffee
...

ROCK6

my hurricane canned food prep is in the form of the chunky soups and stews that can be heated in the container...may be slightly over your budget, but not much... I donate to food bank about 6 months prior to the use by date .. I start adding a can or so to the shopping cart around June... the soups can be extended by adding a handfull converted rice as it simmers

I don’t smoke but love grabbing extra lighters

and the long reach grill lighters work for kerosene wick lanterns too

and the long reach grill lighters work for kerosene wick lanterns too

I'm sure you're aware that bleach has a somewhat short shelf life ~ 1 year.

Be sure to rotate that for maximum strength.

I buy tuna in the foil pouches, mac and cheese and pasta roni angle hair pasta in the box. almost every time we go to wally world. We use these somewhat frequently.

I buy common batteries AAA, AA and 2032 batteries. Sometimes I'll get 9v or D's for lanterns.

As long as your organized and keeping track that's a good plan, but otherwise the theory of ending up with to much of one thing can be a real concern.

I always say, if you cant put hands on a specific prep in 5 minutes or less then its time to start organizing.

https://www.ar15.com/forums/outdoors/prepping-vs-hoarding/17-692163/

With that said I don't really get a little here or there, if I think there is something I need I just go get it.  If I can't afford it, or the cost is a burden, then I don't worry about it.  Of course I prep for realistic scenarios not TEOTWAWKI.

For me the grab here or there is usually replenishing rotated food pantry items.

Borax

Ammo, I feel that it will be in very high demand if the occasion ever arises.

Dry milk
Condensed milk
Crackers
Gatorade powder
Paper plates, bowls and silverware
Batteries
Protein powder
Bleach and sanitizing supplies
Coffee and tea
Survival learning books and other media
Basic Hand tools
Sewing supplies
First aid supplies

Lots of other stuff