It seems from this thread that it isn't a fundamentally difficult thing to do once you have all of the parts/tools required. The issue is getting all the kit for a decent price and having a general idea of the wiring diagrams.
FWIW, I think paying £1000 for it is daft. If your mirrors are folded in and are being smashed off then replacing them with electric motors is just going to make replacing them cost more as well.
With regards to fitting the clocks with the DIS, this isn't necessarily a difficult job either. There are several guides on the web available. Again, the issue is finding parts/coding the new cluster. It's hard to find a DIS cluster for a decent price (if at all) and it needs programming for the immobiliser/mileage, which is something that you can't do with VAGCOM I think?
And it'll actually look like this:
The missing bit at the top is mainly the radio information, which the standard RCD200 can't provide, so it'll be blank most of the time. Also shows the fuel warning icon in that area as well. If you don't have an external temperature gauge (only on cars with climatronic/onboard computers in the clock) then this will need to be retrofitted as well for the temp function to work.