I just can't seem to find a Stealth Boy and I need to do some sneaking.

2 Answers

No NPC sells Stealth Boys, and they are rarer than in Fallout 3. You may find some in locations with Nightkin (in their corpses or around the area). Here's a list with some locations where you can find Stealth Boys.

3

There is a stealth boy in the school house in Goodspring safe also