I would suggest that you establish a budget and the goals for your system (what it will be used for). preferences, etc and post here. Once components are selected, take the list to a "local mom and pop" store or even a local computer club and have them build for you.
Mass market builders use "name" parts for the adds... and most buyers don't look past Intel GPU, nVidia GFX and they're done. Things like HD speed (rpm), PSU, case, fans, MoBo, etc, unless they allow options, are basically "what is the cheapest we can buy this week ?". This is buy no means haphazard "ah we just happened to have a few of these" kinda thing. This **is** how they make their money.
Just like industries with on site power who select daily whether to use power "off the grid" or power their generators with oil or gas, rest assured they practice "on time delivery" and select component choices frequently.
As for shipping, I wouldn't trust the shipping companies to ship it from next door let alone "across the pond".