Nice to see .NET developers in here... Don't you want to make a WPF/Silverlight app as example? 
+1 on seeing other .NET devs here.
As to the OP, not too sure why people would pay for a wrapper that anyone proficient in C# can write within 30 minutes.
I think the value add would be a Silverlight/WPF frontend as Maxim said
Fully, agree. But I think community don't need new MtGox watcher in .NET... We need normal Client with all necessary watchers and trackers and, of course, sexy UI...