I was thinking the same thing. I mean, these are not Toyotas coming off the line. 250 planes will take some time. Or, perhaps this is an inventory clearance sale. Take all 250 and get a Mercedes Benz for free.
The Russians have been too poor to buy new SU-30s.They only operate the older SU-27s,which are being modernised.If they sold off those,they would lose over 60% of their air defense capability!!