A shirt (everyday clothes, nothing special) free--or up to $5 from the thrift shop if it was something awesome like a name-brand nursing top
Pants again, free to $5.
Shoes generic/kids' shoes? no more than $20. if they were running shoes/quality/well-made/designed for foot health, well...up to $100 I guess. Not that I can afford that, but that's one area I think it's worth it to not scrimp. Also, quality shoes can last ten years as opposed to one season, yk?
A haircut Google how to cut your own hair. Nobody in my family's paid for haircuts in like 7 years. Even if you DIY and mess it up, and THEN pay for a cheap fix-cut (say $10), at least you tried to be frugal first!
A massage Find massage therapists that are open to barter, and leverage what you've got!
Nails or pedicure DIY or barter
A 1-hour class for your kid (music/dance/art/yoga/karate/etc.) Depends hugely on what it is, how qualified the teacher is, how much your kids are enjoying/getting out of it, and of course how often he/she is going. For a class that was 1 hour a week, I wouldn't spend more than $40/month personally--but YMMV.
A toy Again, depends hugely on the age of the child, the type of toy, how durable/long-lasting it will be, etc etc. I would spend $$$ on a sturdy wooden handmade thing that my kids woudl adore and that would last for years...but not on a $50 hunk o'plastic that would sit un-played-with a week after purchase. Gnerally the older the kid, the more I take their opinion into account. I won't spend the same on my 4yo as on my 12yo, yk?
A monthly night out with friends or your spouse Ideally nothing, or rather, the cost of groceries to make a good dinner together, and maybe a cheap bottle of wine. We might go to the theatre once or twice a year, and that will be just the tickets. We spend a lot of time at home instead of going out.