I think you'll be the only person who can really answer if it's going to be a good deal or not. The bundle is a good deal if you're going to be using the default art style in any of your MV games. It'd be a bad deal if you want to avoid the default style or if you end up never getting to the point where you might use the resources. One of the nice things included is the Season Pass, which, among other things, has a ton of artwork for a child generator. If you use the default style portraits or sprites in any portion of your game this would be useful.
There are a lot of free assets, and I think it's a shame they aren't used more, but it has the problem that all free things do. You'll find a lot of low quality stuff, a lot of default style, a bunch of stuff that's it's own style but can't be used without the ability to mimic the style and make more, and a few rare things that are original style, good quality, and can be used on it's own if you plan your game around what assets you have. NOTHING is as expansive as the RTP, and without loads of money it's not going to be. Going with free resources is a potential way to go, especially if you are willing to learn how to expand them yourself.
The non-default styles possible from store packs are a bit hit and miss. They're all higher quality and have more stuff in general than the free stuff, but you will have to plan a game around what you have here too. That's just how it's going to go with found assets in general, the only way around this is to either have so many options that you can't think of anything else outside of it or to hire someone/make it yourself. That's an expensive way to go, either with time or money.
Hmm. Have you ever tried to make tilesets before? If not, definitely expect to buy some artwork. Replacing all the artwork is way, way more work than people think it is. If you've never done anything like it before you will burn out before you finish a game. There are some rare folks who can do games all by themselves but I guarantee that their first success was not their first experience with game creation.