Idioms for { repairment is costlier than the price of new }

Question

We often come across situations like:

1. Investment is costlier than profit.
2. Repairment is costlier than the price of new.

I actually want to ask that if there any idiom or Proverb exists in English especially for the two examples, as they exist in my mother tongue.

If so, what are the idioms to express these situations?

Answer 1

for

Repairment is costlier than the price of new.

I would just say "it's cheaper to buy a new one"

not really an idiom, but it is what i hear people say and a quick google search shows it is very common

Answer 2

For maintenance, the idiom or actuality is :

Preventative maintenance is expensive, breakdowns are very expensive.