Finally I follow your advice, I still have a small space where I can put a DER EE in vertical position on my shelf and add Kelvin clips myself.
I order one on ebay Japan with options with free shipping for a very low price (87€) and arrive in just 2 weeks.
I was very surprised that it pass customs
I normally don't worry with customs clearance, I know someone who work there it is usually cleared in one day
If I need to get better precision on resistors I still have my 7 1/2 and 8 1/2 meter.