I should think quite a lot
E-bay was launched in Russia just 3 weeks ago and it's impossible to sell anything there due to restrictions, the only possibility is to buy.
Ebay delayed its Russia launch
For people, who live in the Western world, these plane pieces are in the first place forensic evidence and may cost some money.
Of course, the area should have been secured according to the Western rules we are used to, I think that Russian security guys thought about securing valuable stuff, the luggage of the passengers.
And a normal Russian civilian will not steal anything that has no value for him when guys from the Federal Security Service hang around.