For the hobbyists (like crackers) it might be expensive (how can they spend 300$ if they can't even afford a 5$ shareware ), but considering the fact that IDA is made for a more professional context (e.g. security, antivirus, as has been said before) I think it's an adequate price.. It's also a very special tool, as the majority of computer users doesn't even know about disassemblers. Thus the number of sold licences will be accordingly small, demanding a higher price.
I also understand that software vendors refuse to give support to people that use non-licensed software (this includes demo software..). Man big companies selling professional software only give support to customers having paid for support.