Stay away from artsy hand-made Peruvian ocarinas. They're not usually well tuned.
Really, though, that only matters if the thing is going to be played. If the ocarina is more in the nature of a tchotchke then those Peruvian ones can be great.
If the person receiving the ocarina is a musician who already knows how to play one, it's best to look at what they have already to make your choice. There's a lot of different styles: sweet potato, inline, pendant, etc. There's also mutli-chambered ocarinas that help overcome the limited note range of the instrument. Each of these has different play styles and fingerings, so it's important to get something in a similar style to what the person is already playing.
If the ocarina is *intended* to be played, but the receiver has never played one before, it's probably best to stick to the $20-ish range, rather than shelling out a couple Benjamins for a professional model.
This is a decent starter instrument made by a reputable company.