My impression is that the refits aren't expensive.
It becomes expensive when you start putting in high performance and long range radars, which does not appear to be the case.
There was a Type-54 cost breakdown estimate, where the Type-54 weapons and electronics came to $185M, and the rest of the ship was $162M
So if they keep the hull, and then just fit in Frigate level weapons and electronics, it should still result in a cost effective overhaul for a Frigate.
I also think so, considering all these components have also been volume produced which reduces their costs further.
I would think the main concern is that if all the upgrades would fit within the ship's electrical budget, and how they would affect the ship's displacement, balance and handling. For example the Shtil arm launcher and its 24 missile magazine vs. the 16 missile VLS + 24 missile HHQ-10. I think the HHQ-10 was added to help offset the weight difference, and for that reason I want to see the rear clearly if HHQ-10s were added too, even if just to balance off, or some other item was used to compensate for the weight like decoys.
If YJ-12 is 2500kg according to Wiki and Moskit is 4,500kg according to Wiki, would have required 14 YJ-12s to compensate the weight of 8 Moskits. I don't think you can put 7 YJ-12s on each side of the ship, more likely at the max, six missiles, three rows of two, for a total of 12 YJ-12. That still leaves you with some negative weight surplus.
One completely new item the original Sovremenny doesn't have is the equivalent of the Type 364 radar, which is now fitted on top of a second mast behind the funnel. I don't think this radar unit would weigh much however.