My novels have ranged from 50k to 275k. I did reduce the cost of the 50k novel to 99 cents since I thought it was a bit thin for $2.99. But as long as the story is well-written and you can tell a complete story I think length is one of those subjective things that matters less than the attention it gets.
However, if it is shorter than that, you might want to include a note about word count in the book description. I received a number of "too short" comments on a 19k word novella (even though it was a free giveaway and clearly identified as a novella).