Whats the issue there?
You don't wanna pay up enough for the voice overs?
Is that it? salary issue?
I don't understand why you always have so few people doing voices for every NPC,it was the same thing in Oblivion.
Why not just let someone at your studio do some voice overs?
We all have diffrent voices,so even if someone has a "bad voice" for a game it still works.

Its just annoying when you recognize the same voice for the 10th time on 10 diffrent npc.

Actually, if you look at the credits - you'll see quite a number of voice actors. Here's a link to the imdb page:
http://www.imdb.com/title/tt1073664/fullcredits#cast

There's like three dozen people lending their voices to this game (possibly more, for instance I still don't know who voices Sydney). I think the reason it seems like there aren't that many different voices is that there are so many people who talk to you in the game - and it seems like every "Megaton Settler" or "Wastelander" or "Scavenger" is done by one of two voices (male or female). That is, the hundreds of generic unnamed people you encounter have the same voices.

Post to Fallout 3 forum if you are talking about Fallout 3.

Voice over acting isnt as easy as you think it is - it isnt simply talking into a mic. You need to be able to convey the right emotion into the mic for the statement, without the benefit of being able to participate in the actual conversation and actions - Skilled live action actors are often on record saying just how hard it is...

Exactly. Get any old staff member or the janiter and you`ll instantly notice the difference. When you voice-act, it isn`t just a saying, the voice acter needs to `act` out the words!

p.s. Of course, the janiter could be a part-time voice acter and you may strike lucky!