I need help with Purchasing options and Upgrading with 3820tg

Ok first of all I have been following the 3820tg threads and wanted to say thanks to all for the information you guys are GREAT!.
Now on to my situation.

I would love to purchase the 3820tg and I am travelling so have flexibility in where I can purchase my 3820tg. I am now in Mongolia but have just been in china and Maylasia, will be going to Europe(London first) sometime soon aswell(and china and asia in another 2 weeks). I want at minimum an i5 450m/5650. In Beijing 2 weeks ago I got offered a i5 430 with 4570 video card for 5900 Yuan,(Less than $1000 Australian Dollars....even less in usd quite cheap I thought) The acer site says that they should have 5650 available and up too i7 in china but im not sure where abouts in china, Searching the Online chinese site taobao.com, gives me some nice options in china(i5 5650 combo)...But problems

standard 320g HDD (id like more Gig as I have alot of Photos. How easy is it to switch HDDS and how much more expensive would it be)
2g ram standard...?how much would it cost for 4g and is it easy to replace?
Is it also possible to swap the Chinese win7 OS for English?(i will probably need to ask the retailer).

Other options, Purchase online from germany and get it sent to London I have an address.850 euros
Buy a lesser model with the right ram and HDD from London.

I am looking for the cheapest overall solution(best value for money as im travelling).

Or I could make my way to singapore and get an I7 But im worried about the difference in Price but to be honest mainly in overheating.

So to sum it all up Im a bit confused, Mabye I could purchase the exact model Im looking for In Taiwan or Hong Kong Or Shanghai. The German option Seems great but at <900 USD buying in china and upgrading could work out cheaper if im right?Any advice or expirence would be greatly appreciated. Thanks

 

Bump, I'm sorry my writing style is a but all over the place, but please help especially with the hdd and ram as I will have the chance to buy inchina before the end of the week and will be in Europe in the next2 weeks

 

If you are not too worried about the spec, I would have thought that buying the laptop closest to where you are living would be the better option in case of problems.

 

Thanks for the reply,I'm going to be travelling for about thenext 2/ 3 years so it doesn't matter as much where I buy it from,I have narrowed it down though and I'm not sure still, German version costs 1100 usd roughly and comes with. 640g hdd and 4gram,Chinese version I can get now with english win7(can i reinstall windows in English on the German one?) 320 g hdd and 2g ram )-: but only costs900 usd so I'm still not sure

 

first things first

what will you use this laptop for

 

Primarily photo, video editing and gaming.
I guess I will need 4g ram for basic performance and either way I'd like 7200rm speed hdd but not sure how much those upgrades would cost, slightly unsure how to deal with the German os aswell