Relatively expensive; costing more compared with alternatives (not necessarily luxurious, just comparatively higher-priced).
この店は他の店より割高だが、品質はいい。
This shop is a bit more expensive than others, but the quality is good.
小人数で買うと一人当たりの料金が割高になることがある。
When you buy for a small group, the per-person cost can become relatively high.
セール品でも送料がかかると割高に感じる場合がある。
Even sale items can feel relatively expensive if shipping fees are added.