On the whole, it's cheaper.
BUT.....some things are not that much cheaper.
There are bargains to be had, it's all too easy though to convince yourself that everything is a lot better value than maybe some things actually are.
Personally, I'd buy out there. Just make sure you know how much things cost over here, before you travel....sounds obvious I know.
We found a lot of the bargains were in stores doing specials, BOGOF, BOGOHP etc. The savings were always substantial then.
Oh yes, blah blah blah, customs limits on the way home, etc etc.
someone else will be sure to come along and mention that at some point. I never gave it a second thought myself.
SC