Are you new to calling?
The reason I ask is, if your just learning, yeah you might start out with a cheaper call and intructional DVD to get the basics. If you know how to use one already, I'd recommend going to a cabelas, bass pro, etc. and try out different ones. Just because I can make a certain call sound good, don't mean you will. It's all about are presentation, and the way blow the call. Also, not all duck calls are created equal.
Single reed calls tend to be more versatile. They tend to have more range from low to high, and the ability sound like different ducks such as a young high pitched hen or raspy old hen. But, singles tend to require better air control and less forgiving. Double reeds tends to be more forgiving, and easier to get the hang of. But, not as versatile and singles. There are a few doubles out there that will, but they are more expensive, upper end calls.
Haydel's dr85, echo polycarbonate double reed, echo diamondwood are good, ducky sounding calls and are inexpensive. But are lacking in some areas, at least IMO. I know folks who use them and have success with them. They just don't fit me or my style of calling.