How often do you treat yourself to something new?

Not that often - maybe once every week or two, if I see something new that fits my needs or tastes (and, as you say, is simple and inexpensive).
The most recent is cordyceps powder as an immunity supplement in the hope of fighting a cancer in the corner of my right eye, $20 for a jar the size of three matchboxes. Expensive actually - because the amount I'd need to take: 7g 4 times a day added to a drink or food. It tastes mushroomy, great in stews. However, the cost would mount up to more than I could afford long term.
The alternative medicine, prescribed by the opthamolgist, was drops (chemtherapy) that stung like a red hot poker, caused the skin around to turn red and swell up - funded by Medicare, hence free, but intolerable. I'd rather kill myself than apply those drops 4 times a day - nothing but medieval torture for four months!
So, I take my chances with this one jar of cordyceps immune booster - and if it doesn''t work and I have to die naturally, I accept that as nature doing its thing. Have no fear of death, so its perfectly okay.

Other things new and affordable for me:
- the sound of two channel -billed cuckoos, a series of sqwarks - start at a low pitch, each rises higher, till they finish with a shriek.
- fresh wakame seaweed - delicious and extremely healthy - would have it everyday, but not easy to get
- all forms of soap make my fingernails brittle - now use just water and nail brush, and gloves for garden work
- coffee club in town, a new group of friends, intelligent, kind and funny
- reading, hearing and discussing new ideas
- American Pitbulls can be friendly and love to be petted (most other dogs do too, but i'd always been wary of Pits).
- exploring new places in my area.
- new cooking techniques - using a convection cooktop is not so easy - but MUCH cheaper.
- propagating seeds from last year's veggie and flower crops, [i]much[/i] cheaper than buying seedlings
- internal discoveries through meditation

Actually, there's no end to the new things one can discover if one is open to it. The possibilities are infinite.

It very often as my kids get stuff before I do! I did buy myself a t shirt from my old university last weekend, though.

Depends on my energy level to get out and get/do something new.

I buy my lunch at work on Wednesdays. That’s my treat.

Once a month I go to my fav thrift store north of where I live. It’s a gem of a place that sells great quality items for dirt cheap and it’s rarely busy. I always buy something. Last week I spent $15 and got a dress and two tops.

I also treat myself every month to getting my brows waxed and lashes tinted

Yes, the food treats have to go for me as well; I need to lose 10 to 15 lbs. I did treat myself today to some sales stuff at Marshall's to liven up the Fall wardrobe. It's something I do maybe once every other month.

not very often
actually I rarely get anything for myself except food
I do but foods lik so fancy expensive fruits atleast once in a month 🤦‍♀️

I'm sure you are "skinny as a rail," about the only thing I do is take the family out to eat every payday. I know that's an "us thing," but that's what I enjoy.

Today 😌