As I don't need it too often I want to avoid to try creating a lens correction profile on my own - and as I never did before I'm unsure if I am able to.
I promise you, you are able to. But, 2 things:
1) Don't need it too often? - Lens distortions don't turn off and on. If you need it, you always need it. And with cheap ($200) cameras come cheap sensors and cheap lenses. You definitely could benefit from it, especially if you shoot underwater, the blue channel gets massively distorted. While you can compensate for pincushioning/barrel distortions by eye somewhat, even on the JPEGs, there's nothing you can do about chromatic aberrations. Some plugins can fake it, by using in-painting around the color fringes, but to truly remove tCA you need the RAWs. (once it's been demoasic'd it's nearly impossible to truly remove tCA, or adjust white balance correctly, or, or, or... this is why we shoot RAWs.)
2) CHDK, Darktable, dcraw, exiv2, lensfun, etc... most of all of the software you are using is OSS... get in the spirit of things and learn to profile your lenses. You will gain a better understanding, and more knowledge is always a good thing, not to mention you may help out another less-capable D30 user if you upload your results to the lensfun forum, or hugin/panotools, or both! Avoid it? NO! Embrace it! :-)
Yes, they can be time consuming to create, especially in that you have to do everything twice if you want underwater corrections as well as above... but how much or how little you do is up to you. If you mainly shoot above water at fully wide and fully zoomed? Just start with correcting those two positions. Come back later and do the rest. Or get motivated and do it all at once!
If you Google for creating lens profiles you will get many hits...
... and if you REALLY really don't think you can handle it, and want to give it to someone else to do the work for you, Torsten Bronger does allow uploads for image calibration... but please make a donation to the project if you go the lazy route: Lensfun calibration