I'm interested in finding something out. In Delphi the default since the begining when buying components has been to be able to purchase them with source (even if it might be a slightly more expensive option). This made sense in Delphi for a number of reasons, firstly Borland led the way by providing the full source of the VCL with every install of Delphi, but also having the source was considered essential since when you upgraded Delphi you had to recompile and sometimes Authors went out of business.
I'm interested in finding out whether any Delphi component writers out there have ever had reason to regret selling their component 'with source'? Has someone tried to release a competing product based on your code, or passed it off as their own?
The reason I ask is because it still seems to be the exception rather than the norm to provide a 'with source' option when purchasing an ActiveX control or a .NET assembly. Maybe a reassurance that people don't want the source for nefarious purposes might convince more component writers to allow source code to be purchased along with the component.