I'm not sure that $5000 would count as significant revenue (I'd prefer an extra zero on that) but I suppose it's reasonable that if you earn enough from Delphi to pay for it, you should.

I can't find the new pricing on the website (everything is free trial / request a quote) but I remember the last time I saw pricing it was so much that I opted to kill the one Delphi-made product I had rather than upgrade. I'm using Xojo instead for my cross-platform RAD development now.