I still buy most of my clothes and a lot of bike stuff locally because I have a knack for getting stuff in sales etc. or because I know that the next order of X that a shop makes will be at a higher price because of changes in the exchange rate etc. (this doesn't happen with online retailers because they are selling stuff at a much faster rate).
I don't think all retailers are dodgy/crooks because I have some understanding of what their balance sheets look like and that some of them will have to pay all of their import/freight charges (= not much difference between their prices and UK RRP) whereas others will have suppliers that are willing to pay all of their import/freight charges (= being able to take the full 15% off and possibly absorb the costs of GST too, even being able to afford not to add it to their prices in some cases).
Perhaps it is a bit 'old-fashioned', but I have gotten to know several local retailers fairly well over the years and I'm not to going to walk into their shops, take up their time, and then go and order whatever I wanted online in order to save a few quid (and I really hate the people who walk into a shop with every intention of doing just that).
It is only a few quid though, which is why you'll never see me in a shop selling expensive consumer electronics unless I'm just browsing or unless I know the owner.
As others have said, the worst thing about the Think Twice - Buy Local campaign is the sheer hyprocrisy of it when States-endorsed/approved things like the GST import threshold and that new thing that has been set up with Jersey Post are a thorn in the side of local retailers.