Hey guys!! I'm about to buy this beautiful Raleigh Grand Prix

, and it clearly needs some help, but I want to make sure I give it what it needs - I'm no expert on the subject, and Sheldon's site only helped me to understand that there are proprietary parts on this bike, so I'm hoping someone here can help a little further

Pictures are here :
https://www.gotonirvana.com/david4/P1010132.JPG
https://www.gotonirvana.com/david4/P1010133.JPG
https://www.gotonirvana.com/david4/P1010134.JPG
The original specs can be seen here:
http://www.sheldonbrown.com/retroral...grand-prix.jpg
Clearly it's going to need some help around the rear hub, I'm thinking new rear derailleur?, new chain (obviously, lol), new cranks, tires, tubes...I haven't seen it in person yet but I'm thinking the bearings in the bottom bracket might not be good? Also, I would like to upgrade the shifting system and am not sure if I would be able to? (the shifters on the stem get kind of annoying and inconvenient) I don't want to spend a whole lot on this but don't mind sinking a few hundred on the project.
What do you guys think this is going to cost me?
Any help or suggestions on the matter are so greatly appreciated

Happy riding!!