budget macro flash set from yongnuo

You don't mention which camera system this is to work with. However, the twin flash bracket you posted a link to above isn't robust enough to handle two standard flash units. I have one and it works very well with a Canon MT-24EX twin-head macro flash, but that's because the flash heads are very light. Even with Canon's Speedlite 270EX-2 flash gun (their smallest slave flash) the bracket isn't robust enough to hold it steady.

I think you should look at using a single, diffused, off-camera flashgun (as another poster has suggested) first. When you've explored the possibilities provided by that, then you might want to move onto a twin flash setup. However, a twin flash setup isn't "better" than a single flash for macro, just different.

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Check out my galleries (lots of macros) at :
http://www.pbase.com/cjed