Is it worth to get a Bianchi Caurus 909 and rebuild some parts? I'm planning to get a Bianchi Caurus 909 2nd hand for city bike and some long rides (30 km average) whenever i want to visit another city for example. The thing is if it worths to get the bike and change the gears, maybe the brakes, handlebar plus the maintenance. I've asked a bicycle guy from my city and he said it would cost something like 80 euros to clean and change its parts that i've mentioned on top.

I'd like to convert this:


To this: 



Thanks!
From economical standpoint, rebuilding bicycles is almost always unreasonable. For the same amount of money spent on replacement components, it is often possible to buy a new decent bicycle of the same or better level, thus saving workshop time.

If, however, money is not a deciding factor for starting a rebuild, then the answer depends on whether you like spending your time with bike tinkering, and have no other better/enjoyable things to do. If you do enjoy working on your bikes, restoring old things, or want to learn new skills and things, then go for it — wrenching on a bike is often a rewarding experience.