spare no expense; regardless of cost
Fixed expression meaning to do something without worrying about the cost; often used when someone is willing to spend a lot of money on something they value.
See also: 金に糸目をつけない
He spares no expense in continuing to modify his hobby car.
We spared no expense on this project and gathered the best equipment.
The non-negative form; 金に糸目をつけず is the continuative/negative-te form used adverbially.
Standard kanji spelling for this fixed expression.
Variant using 付けず; both spellings are used.
Literally 'without tying a thread on money'; 糸目 (thread) refers to a purse string, so the image is of not closing one's purse, i.e., spending freely.