If it's mainly for use as BUG and you don't want to spend a whole lot then go with the Kel Tec.
If you still don't want to spend a whole lot, but want to move up to a decent 9mm that's a decent shooter and don't mind that it's not really a "pocket gun" you may want to look at the Kahr CW9. I have had absolutely no issues with it with 900 rounds through it. It's thin and reliable. I wouldn't call it a pocket gun but it will disappear just about any other way you carry it.
If you don't spending more then Kahr has a few smaller models in 9 and .45 that are very good quality, just more $$$.
If you still don't want to spend a whole lot, but want to move up to a decent 9mm that's a decent shooter and don't mind that it's not really a "pocket gun" you may want to look at the Kahr CW9. I have had absolutely no issues with it with 900 rounds through it. It's thin and reliable. I wouldn't call it a pocket gun but it will disappear just about any other way you carry it.
If you don't spending more then Kahr has a few smaller models in 9 and .45 that are very good quality, just more $$$.