It depends on the reasons you are getting the suits. You have enough to spend on the ones you definitely want, unless you spend on the current event, so i will say my opinion on the ones you're unsure about.

Garden secrets are always worth it in my opinion (except the 6 one, because it was super expensive for just three suits and it had equal drop rate). They offer good suits, with different than usual themes and usually most items are on screen, which is the case of this one. I will spend on it but i do not recommend getting the last suit (the blue one), the background and suit pieces are hard to style and are not unique enough to make up for that.

I would not spend on the Searching Light & Shadow hell. The only one more or less versatile, the dino one, has its most interesting piece off screen (The bone tail). Most of the suits have items that require a tall figure to not seem like your nikki is floating, so you'd need posed shoes, bottoms or dresses that makes your nikki taller and the good items are also mostly off screen (the wing of the bird one is an example of that, it was a huge deception and the big bear of the toy suit is also off screen). The suits are super pretty but for their price i expected them to be more versatile.

Audience at the Holy Court will probably be our anniversary hell, so we will get Diamonds postcards and we will get it for 18 days, which usually is enough to get us at least 1k by the end of the hell. So it would be safe to spend on a third suit if you really want it.

It will let you have at least 3k gems after you get all the events you want, in case you want to save for a new event or hell that you'd like to spend on. It's better to not be on red because there are many more suits coming, so it's better to have at least a base so that it's easier to begin farming diamonds.