This little spell is getting a lot of hype lately due to some cool tricks it can help you do in commander format. Of course, it is currently overpriced, but don't expect it to drop too much as the card is really good.
Usually, rare spells seem to settle at around $5 mark, which is a perfect place for Mystic Reflection. If it gains popularity in other constructed formats as some kind of a miraculous combo breaker, then it can go above $5 a piece.
Most players will still prefer to play classic counterspells, and that may put Mystic Reflection into a niche market.