Personally I've not had need of a calibrator myself (my screens look good to me, and I don't work in a field which requires any level of display accuracy), so I'm afraid I can't provide any recommendations that you couldn't pull off the average review site. I can start you off with a web search, I suppose.
Regarding the uneven brightness, no, I don't believe any amount of calibration will fix that. It relates to the backlight that lives behind the actual LCD display. Some say you can improve matters by slightly squeezing the darker areas (forcing the LCD into closer proximity to the light - note "slightly", if you suspect you'll crush it, don't even try!), and others find that the effect is much less noticeable if they simply turn their overall display brightness up higher. In some cases, you'll find that simply tilting the screen on a different angle to your eyes is enough to make it appear even.
I'm afraid the only other fix is... a new screen, which is once again subject to the roulette of part availability. Odds are good that you'd get another one which looks exactly the same as the one you've got.
I'm afraid i won' get a screen replacement as I have already had 3 and as I mentioned earlier Apple claims it's within specifications.
Do the pictures look similar too you, or does one appear to be darker?