The monochromatic final episode of Top wo Nerae had nothing to do with the budget, that was a stylistic choice. It costs the same amount of money to animate in grayscale as it does to animate in color.
What was a budget-saving measure, though, was how the final fight was mostly still shots. And even then, they handled that shit extremely well and it didn't take away from the MAJESTY of the whole thing.
The still-shot shortcut wasn't unique to the final episode, it was evident up through Episode IV IIRC. Most of the space insects were stills that got cut up by a heavily animated Gunbuster,
I don't 100% buy the grey scale as purely stylistic, although let me note that was my original impression before certain people contaminated that line of thinking.
My reasoning is Gainax tends to blend time when it cost-saves with "experiments" of style, and calls the whole package style, when it might just be them using an experiment as cover. And the experiments always end up following very expensive episodes. NGE is the stereotypical example, I think of GL's episode 4, animated by Osamu Kobayashi. It followed episode 3, which was animated by a bottom-tier studio like Xebec yet looked VERY VERY GOOD, whereas the Kobayashi-led Gainax team put out an extremely awful quality episode but disguised it by having Kobayashi on board. Beck that episode was not, in the same way Giant Robo is not Shin Mazinger.
Follow that with the Rossiu near-monochrome dirt poor village (compared with Simon's underground village from earlier) and the original excised footage from Episode 6, and it's clear to me Gainax shot its wad with Episodes I and VII and tried to make up for it by spreading the love to the other episodes.
While Abenobashi and Mahoromatic were pretty much uniform in terms of animation quality, the shows themselves were kind of… iffy. Mahoro was pretty alright, but Abenobashi was pretty eh.
Call me nuts, but in recent months I've started to grow attracted to the surreal mind-rape approaches taken to weird shows like Abenobashi. It's much more memorable, although not necessarily in a good way. Mahoro was incredibly depressing and horrifying, on top of driving people insane - although not as nuts as Abenobashi I still preferred Abenobashi more, partially because of the references.
You're joking, right? Nanoha and Fate are totally gay for eacher, the staff gave up on trying to hide that a LONG time ago.
I'm half-joking. It's because the Nanoha staff seem to play up the "romance" in an almost parodic way, but keep it kosher to the point it's only an undertone that people want to see really badly.
A better example…uh, Claymore.