I seems to me that web sites offer more variety of kits and specific parts/decals, etc.
I went to my local Hobbyland and noticed that prices were comperable to web stores, (considering price, tax and gas).
LHS's can't maintain stock and have to be generic in their selections of kits and when you can't find what you want, where do you go?
Along with the virtual catalongs and pics of items available, webstores are on top. Considering the cost of gas and the 'hit & miss' (hoping to find what you want); the cost of S/H aren't that far off in expenditures.
In my area most of the LHS are into R/C and only maintain a limited amount of kits and for me