a person who would save, gain, or extort money by any means

A skinflint is a person considered so miserly that he would even "skin a flint" to save something of it. A flint is a small piece of flintstone used to strike a spark in the tinderbox. The flints in modern day lighters aren't made of flintstone, but rather of Ferrocerium.

A penurious person; a miser; a niggard.

a selfish person who is unwilling to give or spend

a person who tries to get everything out of you, but refuses to give you anything in return