Learn English – the grammar error in this sentence: “We should spend more money on education and health and fewer on new technology”

You might want to look into these words:

1. stingy
2. cheap
3. miserly
4. tightfisted

Depending on some other context, you might also want to look at

1. frugal
2. scrimp

I forgot to include skimp! That one was the first one on my mind.
As StoneyB writes, we would say

Don't skimp on your child's education.

I gave a list because I was thinking of other ways to say this. Like "Don't be stingy when it comes to your kids education."

Frugal and thrifty have positive meanings. They are usually used for someone who is careful about how he/she spends money and lives simply and economically.

Miser and stingy have negative connotations and they refer to someone who is reluctant to spend money, no matter what the circumstances.

Cheap has a negative connotation too and refers to someone who doesn't like to spend a lot of money. This person is always looking to buy the lowest cost item (The price of the item is more important than its quality for them)

You may also want to use tight-fisted which has the negative connotation you are looking for and it means:

unwilling to spend money

Here is an example from Cambridge dictionary:

Don't wait for Gillian to buy you a drink - she's too tight-fisted.