I've had almost no luck with white girls in SA.  Anyone else having that problem?  Or any tips?

Pretty much same experience here, Netnoy, although I just had success with one white girl, 28, recently transplanted from the Midwest. PPM very reasonable. Ok personality, slim, reliable, down to earth and fun. Not a beauty, mind you, but decent enough for a brief, if not longer, arrangement. Don't rule all white girls out, but for the most part I've found most success with transplants from Mexico, Columbia, Brazil, specifically. Keep an open mind as one never knows when an outlier will surface from a previously assumed fail.  

I'd have to go and check my notes, but many of my SBs have been white girls.  There's a very large Hispanic population in my area.  Some are recent immigrants.  But most are from old Hispanic families with local roots going back to the 1600s. Accordingly, many of the local SBs identify as Hispanic, although in other settings they would blend in perfectly as white girls.  There are nearly zero AA girls here. I have not experienced either consistently better or worse results based on ethnicity.

Here in the Minneapolis area there is a cornucopia of black and Hispanic chicks.  I agree that young hot white chicks can command a premium.  I think this has always been true. Overall in the US there are 58% white, 19% Hispanic, 13% black and 6% Asian.  
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A while back I did a few younger chicks, but now I'm more interested in late 20's to mid 50's -- just because I feel more comfortable that they really understand the score.   That keeps me from seeing the ridiculously high asks that others report.  I also mostly stick to white girls now, with options for Hispanic and Asian.  Nothing bad to say about the black girls I saw in the past, they were great.  However the racial tensions have been high the last few years, so I don't want to tempt fate.
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Anyhow, if you drop your requirements from top of the line, your options increase.

Out of all my BCDs, only two are non-White: One is a Filipino and the other is a Russian-Mongolian mix (very rare indeed). The Russian-Mongolian mix looks more like Korean. She is very attractive but her bedroom skills leave a lot to be desired. We still keep in touch but I rarely see her because of the mediocre sex and 600 ppm. I don't have too much trouble finding White women in their late twenties to thirties, but the early- to mid-twenties are hard to find because most of them are very flaky probably due to the hundreds of messages they get every day.