The turbo on a Ford Fiesta 2008 TDCi is bust.
How much should I expect to pay?
There are really two routes; dealership and third party (a normal garage mechanic).
If you were to get it done at the dealership, you can expect to pay 10-30% more on top of what an independent garage might charge you. The advantage to going this route is that generally you are going to get what you pay for when it comes to a turbo replacement. There is generally a lot of labour time that goes in to ensuring the part, and any other parts that the new part could effect, works perfectly (that other garages often skip out to save money) in order to avoid other parts failing in the future! You also get genuine parts, a Ford dealer stamp in your service book (which will effect the value of your car on the used market) and the peace of mind knowing that the work is being carried out by properly trained and manufacturer approved mechanics.
Note that the dealerships do often price match within a 5 mile or so radius so you may actually get a really good price there if you do your research first.
The other option is to go the non-dealership route. This is the way most people go due to the inherent price savings associated with this for what most people might assume as being the "same" work done. I would say this is still your best bet for getting the cheapest quote for the work that needs doing, however I will make you aware of the following things that you may want to take note of: - They don't necessarily use manufacturer approved parts - They can skip out some of the tests to ensure there will be no negative knock-on effect to the work being carried out - Will result in a less valuable service history (and therefore resale value of the car)
That being said, I would say that it is okay to have the work done at the garage as long as you understand what you are getting, their inherent advantages and disadvantages and also that you should go to someone you trust or have been recommended to by someone knowledgeable that you trust.
How much should I expect to pay to have a Turbo replaced?
About £150-£200 for a new turbo plus labour, which I can't estimate easily as it varies significantly depending on where you go. Also the time it takes will vary depending on the level of expertise of the mechanic and whether they are having a good day or not (luck). Hence my previous recommendation that was you should go to someone you trust!
If you don't trust anyone then you can come back with only a quote and break it down as follows to find out for yourself whether it is a good value or not.
For example you were quoted £600 for a turbo replacement that would take 4 hours:
So in this example you would be paying £100 per hour for labour and £200 for the part itself. Both of these prices seem quite expensive for a garage (but more reasonable for a dealership). I would make an educated guess that you should pay about £400-500 for the work that you need done at a garage including parts if you can find a reputable, trustworthy garage.
All costs used here are estimates so take them with a pinch of salt and do your own research as prices can change on a regular basis, but the principle remains the same.