I’m very unfamiliar with the rarity of Chinese Unlimited vs. 1st Edition. I know Korean Unlimited is supposed to be more rare and valuable but I don’t know much about Chinese. (of course talking about Base Set).
After a few internet searches there isn’t much that pops up. Mostly just 1st Edition stuff.
What would the price of a 1st Ed box vs an Unlimited box be?
I think Chinese 1st edition booster boxes are more common.
Considering Individual cards, there are a lot of Chinese unlimited theme decks so ninetails, gyarados, mewtwo, hitmonchan are quite common. Everything else in unlimited holo is quite rare.
compared to other languages I would say they are niche.
chinese unlimited is rarer than chinese 1st edition 
but nowhere near the level of korean unlimited as korean unlimited is near impossible to get but chinese unlimited is easier
so goes korean unlimited chinese unlimited chinese 1st edition and korean 1st edition in that order of how easy is it to get
This is bang on. Exactly how I’ve found it and I’ve been messing with these for many years.