ALA is miles cheaper to buy in the US. I recently bought some R-ALA from iherb.com, it was really cheap but I got hit with a £16 customs charge when it arrived in the UK. Ouch.
I have bought some of the German stuff which has been mentioned on here, I didn't like it.
I have found there is a big difference in quality of ALA products, I have settled on Doctor's Best now, I think.
I have recently changed to yet another different brand of R-ALA and my neuropathy has suddenly become a lot worse, so I'm going to have to shell out for some more DB.
I have definitely found the R-ALA variety to be more effective than the racemic version, particularly the "stabilised" variety which seemed to help my neuropathy the most.