有点儿 often gives a small, personal evaluation of how something feels right now. In 有点儿贵, the speaker is saying that the price feels slightly too high; this pattern commonly carries a mildly negative judgment.
一点儿 makes a different move. After an adjective or verb, it asks for or describes a small adjustment—便宜一点儿 means “a bit cheaper,” and 吃一点儿 means “eat a little.” Before a noun, 一点儿 simply measures a small amount. The English gloss may be the same, but 有点儿 evaluates the present state while 一点儿 points to an amount or a shift along a scale.
