Price sounds about right.
Basically you have three main options.
1. Buy Alfa genuine parts - Fit.
2. Buy replacement bushes - push out, re-fit, fit.
3. Buy powerflex replacement bushes - push out, fiddle about, re-fit, fit.
They are listed by the most expensive to the cheapest. Each option both have their pros and cons.
There is also the 4th option to try to source other OEM manufacturer replacements, there is a thread started by CrispDust on this I believe.
Personally, I choose to powerflex the entire rear end and I'm very happy with the results, but expectations differ.
My advice? Grab a cup of tea, sit down and do a search in this forum for "springpan". You will find loads of information in this lounge on the rear sus of your GTV. Digest, and you should be able to come to an informed dicision on how you want to approach it.
A good alfa specialist should be happy to work either of the first three options for you, or if like me you have experience with this sort of work, you can do it yourself.
Best of luck