cost of upgrading computer ?

smokey the bear SG

hi i need to get some stuff for my computer, but i need help with the pricing and brands.

2 fans

1dvd drive

1 tube of thermal compound for cpu and maybe a graphics card. i will most probably go to sim lim square after my exams to get them, i am looking for the lowest possible price any suggestions for brands ?

GamerAtHeart SG

All these are cheap. Fan depends on size maybe cost less than 20, dvd depend on internal or external less than 100. And thermal compound less than 15.