I certainly wouldn't pay £900 for economy. If you buy at the right time it should be more like £600, maybe £700 direct. You can certainly get for around £500 indirect- have a look at Qatar, Emirates, Turkish etc as well as Etihad. Qatar will earn you BA avios and tier points as well.

If prices are way higher than that now then my advice would be to wait.

Also note that even if you intend to use BA miles (avios) you'll still pay a fair few hundred in fees in WT. Best to use for a higher cabin if you can.