Cheap Flash vs. Pricier Flash

[naaaach]

I might get bashed for starting another products comparison thread. But I'm on a budget, and I want to buy a flash. I found the Yongnuo flash online for about 80 bucks, one that would work with my D90. And then I saw an offer for a brand new SB-600 at 200 bucks.

In the long-run, which would prove to be better? As for other accessories, I'll probably have to save on money and go with DIY diffusers or cheaper remote triggers. But I'm not sure if paying 200 vs. 80 will be worth it in the long run if I won't be using all the features of the SB600 (actually, I haven't studied all the features yet, though the Yongnuo manufacturer said their product line is at the same tier). All I want to do with my flash is to take portraits without harsh lighting. Or if I get a wireless trigger, I can get more creative with some of my photography.

I know that the 600 can't be used as masters but if I buy another flash soon, I'll probably save up for an 800 or something that I can use as a master.

I was reading through Strobist, and well, mixed opinions got me thinking. What would you say?

 

[KmH]

The smaller a light source is, the harsher the light is, and the sharper shadow edges are.

A hot shoe flash unit is a small light source.

A hot shoe strobe light can be made to appear larger by firing it into a light modifier, like a photographic umbrella, a soft box, or bouncing the light off a wall or a ceiling. That softens the light and the shadow edges by letting the light wrap around the subject.
The small diffusers that fit right onto a hot shoe light don't make the light source any larger. Mostly they just scatter light and waste flashed llight power.

 

[Boomn4x4]

Which model of Yongnu are you talking about... I did a quick google search, and the ones I'm finding sounding quite equivalent to the SB600 in that $80 price range... some don't even support TTL