So I've got the kit with the 22mm and the 18-55. I've got the adapter and flashgun and so far it's cost me around £250. Great value!!!
So I'm now eying up the 11-22......which will cost me more than all the rest put together. I know it's a nice lens but it's kinda hard to justify.
It doesnt (stop). Look at what other mirrorless vendors offer. Sony E, Fuji X, Panasonic m43 and Samsung NX.
1. They offer 2/3-1 stop more light at max. FL (imo negligible on a UWA)
2. They offer more UWA. They usually start at 14-15mm equiv (The 11-22 starts at roughly 18mm equiv.). This can be a big deal depending on your usage
3. They are MUCH larger. (None of the above will easily fit into a coat pocket when attached to a body while the M + 11-22 does)
4. And consequently, they take much larger filters (a large thread quality ND can be fairly costly)
5. Optically, the 11-22 is on par with most of them, or actually a little better at the same FL/aperture.
6. Finally, they cost almost twice as much as the 11-22, partially even more
The only thing comparable in size and price is the Olympus UWA. It's not a bad lens but the 11-22 is noticeably better. If you still think this lens is expensive, interchangeable lens cameras might not be the right thing for you. There are many lenses out there that cost a lot more than the 11-22 which I'd still consider a good deal. The 11-22 is quite exceptional.