I would recommend a Hohner Special 20. Same price range, easily available, and, in my opinion, slightly easier to play than the Marine Band.

There are a number of other good models and brands out there now that other players approve of, but I haven't tried many of them, and they aren't as likely to be stocked in your corner music store.

Having said that - a lot of people swear by the Lee Oskars, but they are more expensive.   Many people find they last longer, though. But I don't.

To start off, I would get a D. Being a higher key, it is a little easier to get going on for blues harp than, say, an A. You will want to get an A before long though, as many guitarists play a lot of blues in E (see above post re: cross-harp - also known as 'second position').