You can get cheaper seats both for the next stage and for the pram stage. The cybex car seat adapters fit loads of brands:
Joie (except Juva)
Maxi Cosi
Cybex
Nuna
Avionaut
Besafe
Britax Babysafe i-size 3 or i-sense, and anything newer (the older models need Britax specific adapters).
Recaro
Unless stated otherwise all the models from that brand fit. A few others might as well but those are the ones that I know for sure use those adapters.
If you're after extended rear facing for the second stage then you may want to look at the Swedish style seats anyway, Axkid or Britax (max way/max way plus) which are still about £200-300, but they last from approx 1 year up to 6/7 years so a bit better than 3-4 years.
IMO, the rotation on the Cloud seat is a bit of a gimmick, because you don't really need the rotation on an infant car seat as you take it in and out of the car every time. It's useful for the second stage one if you go for the modular seat that fits onto the same car base. But that does bring your base out of the running if you have a second baby and wanted to use the Cloud seat again.
The recline is also not quite flat enough to replace a carrycot, it's not flat enough to be considered safe for unsupervised sleep, although it does go flatter than a normal car seat.
Bear in mind the base is also an extra £200, so it's £440 for the Cloud Z with the base which is a lot of money in my opinion. It's a lovely seat but considering you only use it for about a year I always think it's bonkers! If you get the Sirona Z which is the next-stage seat that fits onto the same base that's another £299 (so just as expensive as the standalone version!)
Unfortunately car seats are very much front loaded in price as in you pay £££ for the smaller size ones that are suitable for younger babies because they just grow so fast when they're tiny (and need that much more protection). Once they're about 4 or 5 you can swap to a high backed booster which costs about £60-100 and it will last them until they are about 10 or 12! It's the first one or two seats which are expensive.
I will do another post about the birth to 4 years ones because this got a bit long 