Spoil the ship for a ha’p’orth/ha’pennyworth of tar
Definition 1 of 1
Pro Tip 1/3Idiom Origin
Understand that this phrase originates from naval culture where not using enough tar could cause a ship to leak and decay. 
Maintaining attention to detail is crucial; don't spoil the ship for a ha’p’orth of tar.
Pro Tip 2/3British Phrase
Remember it's a primarily British expression, so it's not as commonly used or understood outside the UK. 
When I used 'spoil the ship for a ha’p’orth of tar' in the US, they were confused.
Pro Tip 3/3Modern Relevance
Though historical, it applies today when small savings cause big problems. 
By buying cheap, unreliable tools, he spoilt the ship for a ha’p’orth of tar.