it is still horribly priced regardless of its anti infantry capabilities since it is effectively checked by a single panther. it should cost less than a regular tiger tank.
whereas it takes 2 su85s to check a single tiger tank which cost about as much as a tiger tank, mp and fuel wise.
IS-2 is quite good. It does have to be careful around a dedicated tank killer, but it is very good.
This comes down to the Soviets relying on multiple units and munitions to defeat, shot for shot, better Ost units. Use AT nades, a mine, button, or ram to give your single SU85 the advantage over the Tiger. An SU85 + AT nade is more than enough of a threat to a Tiger.
When I see an IS2 as a Ost player I have to either direct a Tiger away to engage it or a Panther with AT support, since head to head a panther can lose to an IS2. If the Tiger gets a damaged engine the IS2 can circle strafe it all day.
Don't forget to get a Panther the Ost player still needs to go T4, and then build the building, and then construct the panther. The IS-2 player needs only wait for the CP's, so its cost reflects that.