I am able to afford one but it's still a lot! Is it worth it?

At this time not really, they are pretty inflated since people are buying them as Luminaire gifts for people. With a Subeautique Invitation you are allowed to purchase one item, and the prices range from around 150k - 200k per item.

are usually a pretty common random event. I know I have a nice stack saved up in my vault.

Great thanks for the help :)

I think they are also currently inflated because the random event they come from has taken a back seat to the snow fairy random events. I know I haven't had a Subeautique invitation random event since I re-joined Subeta at the start of December.

Wait for an event that requires a lot of screen refreshing and the like, and you will see these things drop in price.

Id say they are worth having, but not sure about buying them. if I were to buy one while inflated [only if I was completely out in my vault] I then am stingy on what I purchase with it. Thou I am even with random events. I price to see if buying it in the subq is worth the invite price + the price you pay there, compared to user shop. If its worth at least 300k more than my buying an invite/item in the shop total I will grab it. But mostly my invites are reserved for new or inflated items ;D

Yeah, if the item is work quite a bit, then it's worth buying an invitation. But I'd just wait until I found one, honestly.