The cost of buying the extra 4 squad slots: 490, 990, 1490, 1990
6 campaigns, 12 different factions = 12 different payout cues
each payout cue = numbers listed above = total of 4,960 gold
4,960 gold x 12 sides = 59,520 gold to get all sides 10 slots
BUT, stalingrad gave squad slots, so 59,520 - 9,920 = 49,600
to get 9,920, take 490+990+1490+1990 then times it by 2
49,600 is the amount of gold one would have if all 10 slots
(if the one also had the stalingrad access pass on account)
the merge changes a fair bit of things = all slots back to 4
6 for premium account, with the options of buying back 4
these 4 will now be TIED to the WHOLE of its new FACTION
WESTERN ALLIES - USA/UK
EASTERN ALLIES - USSR
AXIS FORCES - GER/ITA/JP
USSR and GER faction will get +3 slots if had stalingrad pass
(this is worth 2970 x 2 = 5940 gold of savings for the player)
WESTERN ALLIES = 4960 (unchanged, buy back 4)
EASTERN ALLIES = 1990 (changed, buy back 1)
AXIS FORCE - GER/ITA = 1990 (changed, buy back 1)
AXIS FORCE - JP = 4960 (unchanged, buy back 4)
TOTAL AMOUNT TO SPEND FOR 10 SLOTS IS 13,900 GOLD AFTER MERGE
49,600 GOLD (on refund) - 13,900 GOLD (on rebuy) = 35,700 GOLD
35,700 gold is the total added amount
(after getting all faction slots back to 10)
TLDR: If you have stalingrad access pass and all squad slots at 10 for all 12 campaign sides, you should expect a refund of 49,600 gold to your enlisted account. 35,700 gold after getting all factions back to 10 slots after the merge.
Note: this entire post assumes you purchased your squad slots at full cost and not during a discount event.