uncostly

adjective, cost·li·er, cost·li·est.

1. costing much; expensive; high in price: a costly emerald bracelet; costly medical care.
2. resulting in great expense: The upkeep of such a large house is costly.
3. resulting in great detriment: It was a costly mistake because no one ever trusted him again.
4. of great value; very valuable; sumptuous.
5. lavish; extravagant.

adjective -lier or -liest

1. of great price or value; expensive
2. entailing great loss or sacrificea costly victory
3. splendid; lavish

adj.late 14c., from cost + -ly (1). Earlier formation with the same sense were costful (mid-13c.), costious (mid-14c.).