well, since you don't say where you are, I can't say what will be
available in your local market.
but since what you are asking about is carveability, I can recommend,
in no particular order, basswood, mahogany (the real stuff), poplar,
avoid woods with stringy grain like fir, ash, most pine, alder, and
woods with a high mineral content like ipe, apatong or teak.
no wood is too hard to be carved. however, the harder the wood the
more of a workout it will be... it's worth it though. a medium-hard
tight grained wood like birch makes a durable carving that takes nice
crisp detail. the king of woods for carving is lignum vitae, which is
one of the hardest woods on the planet.
the bottom line though is that your project won't use a lot of wood.
get some of what you have available in your local market and have a
keeping your tools sharp will be a lot more important to success than
selecting the exact right wood.