If you have some generic black block letters & numbers you can easily do an 8th Air Force NMF bird aside from the Air Division and Bomb Group symbols, as well as any personal markings such as nose art and mission marks. For the earlier OD and Neutral Gray B-17s the color choices are a little more varied. Yellow for serial numbers on all, but the squadron codes can be gray, yellow or even white.
I don't know if you have access to eBay there, or if sellers on eBay will ship to your country and for how much, but doing a quick search there for "1/48 B-17G decals" turned up lots of decal sheets in your price range.
F is for FIRE, That burns down the whole town!
U is for URANIUM... BOMBS!
N is for NO SURVIVORS...
- Plankton
LSM