Pfft. You call yourself a tester... you may well be one. But what difference will that make to MS? I mean sure, some of the "testers" will help iron out the bugs... but TBH, I think it's good that MS let us play with their OS before they make is pay for it.
If they didnt release the Release Candidate you wouldn't be able to play with Windows 7.... So I wouldnt complain about not getting a bigger discount just for taking advantage of their offerings!