Artem, forget it, it is not worth the money... once back in Russia, just buy yourself a used E53 with enough life left in it to last you for however many months you will be there, then sell it and go back...
I moved around with the cars, and while most civilized countries will let you have your car imported free of tax if you prove ownership beyond specified period of time (6-12 months in most cases), in Russia this will not fly... as a matter of fact, even in the US I almost ran into an issue with the customs, but luckily, i kept my X5 registration up for the few years it was overseas ($36 a year for PA registration was a little price for a peace of mind - but I ended up paying customs dues for my own booze that came back to the US... next time i am leaving my collection at my mom's house!!!)
so... just get yourself another car while there... and call it a day...