Why would Toei need a monster of a budget? 2 of the most well known Sci-fi series, Doctor Who and Star Trek, are infamous for their abysmal budgets.

Matrix has a point. Unless they were going to do everything in HD CGI, there's no need for a gigantic budget. Innovation comes from having very small resources, not with gigantic budgets.

Essentially this.
An empty sound stage, a swivel chair, some cardboard boxes, and grey paint is all that's needed to make a captain's deck, for example. It might not look as amazing as the million dollar sets, but if the characters and writing are strong enough, they could sell it and convince audiences otherwise.

Actually, sci-fi since about a few decades ago has been generally quite costly, more than other kinds of TV shows.

That said, Super Sentai is a special effects show, so they have experience in balancing budgets. Plus if Power Rangers In Space and Lost Galaxy can do it, I see no reason why Super Sentai can't.

But it's unnecessary. They spend thousands to have a CG rendering of a ship flying through space. It does nothing but move across a backdrop of stars.
It really feels that they spend money solely so that they can say "At least we didn't have to resort to dangling a prop on a string."

I'm against cutting corners when unnecessary, but many sci-fi series of late seem to have forgotten that the wonder and charm comes from the imagination of the viewer, not the budget of the producer. They don't need to spend millions trying to explain every fantastic element and stupid alien props.

And Lost Galaxy didn't really do it. Outside of establishing shots of Terra Venture, it was all planetary. In Space, on the other hand...

Yup, that's what shows like Doctor Who do. Use familiar (and cheap) objects to create wonder and excitement.

Creating the ship shouldn't be so hard. Set aside the budget usually reserved for mecha and make the ship the mecha. No different from using the Gokai Galleon or Megaship props.

I've been toying around with something based on Norse mythology lately. No idea why.

I know this isn't exactly answering the question, but you know what'd be great? Another team of evil Rangers.

Despite the all out awesome of the Psycho Rangers, they've never really done anything like that again since. Sure the Rangers often find themselves fighting evil copies, but there is just something awesome about Rangers fighting other Rangers with their own unique powers and ideals.

Give them a Megazord too. Modular as they've been lately, one made up entirely of option/addon parts that the good guys later acquire for their own use just makes sense.

Yes so much to this. Really, we haven't gotten any purely evil rangers in a very long time. They're either clones, or they start off evil and turn good. We need outright villainous rangers again.