I would like to point out that lucky board have a better cost than panic buy on average--it cost 20 coupon to get 1 dice which at minimal give 5 pts, it takes 7 to get a med thread, ergo it is a max of 28 coupon. However, with the chance of getting 10 pts, it's actually lower than 28, more like 25 that way. That's not to mention the free roll you could get(from free roll spot, not free dice) and the fact that the board gives stuff too, including med thread even if you consider everything else to be useless(there is completion pack too blah blah blah)
In any case, depend on how much you value the "other stuff" you get in luckyboard, I'd rate the cost of a med thread there between 10 to 24 coupon--10 if you value other stuff highly and 24 if you don't value them at all.
Second, I would like to point out that full growth value does not equal auto upgrade, what it guarantees is that the NEXT roll is going to be an upgrade. So with a growth bar of X, you might require X+1 roll to get the upgrade at maximal. So your number is low on that front by 1.
Of course, usually you end up needing less, but I guess you are not going for what is expected (and I have no idea how that can even be found out w/o knowing the code. You'd have to collect shist ton of data)
Add that to SA farming... well, I'd say ftp realistically is going to look at a tab of around 180k to get the armor maxed maybe. It's this high because panic buy is actually more or less the only way for you to get adv thread. Maybe you can get it cheaper if you save a ton of coupon and get it all at once at some 40% discount event or something...