This is why I don't recommend buying any Russian equipment. Those Russians don't know how to do business.
While the Chinese are reliable suppliers, apparently, the J-10B do not have AESA (Active Electronically Scanned Array), still uses PESA (Passive Electronically Scanned Array).
http://www.defence.pk/forums/china-defence/108939-j-10b-equip-aesa-radar.html
BAF should aim for aircraft that have AESA. This one important step that it would have to take to become a world-class air force.
There is a reason why I am insistent on the F-16. It is a robust jet, good technology, easily available, reliable and a cost-effective aircraft. It is better to have a small number of good aircraft with which BAF can familiarize with, rather than having large numbers of cheap aircraft.
And even if the Chinese jets have AESA, they will be a limited option - guaranteed.
Bangladesh should aim for self-sufficiency within its military industry. Western know-how would be a good thing.