Note:
This analysis is intended to help those of us interested in permanent unlocks. If you want consumables for warzone, this won't help you.

Pack Descriptions:
Silver: Gives you 2 permanent unlocks which are common, uncommon, or rare. Costs 5000 RP.
Bronze: Has a "chance" of giving you a permanent common unlock. Costs 1250 RP.

1: What is the probability of receiving a common unlock from a Bronze pack?
To answer this, I opened 40 bronze packs. 28 of those packs contained common unlocks, and 12 only contained consumables. From this, I'm concluding that 2/3 of bronze packs contain common unlocks.

2: What is the cost-per-unlock for bronze packs?
From the above experiment, packs containing unlocks each had 425 RP worth of items. The remainder had 500 RP worth. If we assume you're going to sell all of these immediately after opening a pack, that means the weighted-average cost of the bronze pack is 1250 - (500 + 450 + 450) / 3 = 800 RP. That's the "real" cost of bronze packs. If you're getting a common unlock 2/3 of the time at that price, it means that common unlocks cost about (800 * 3) / 2 = 1200 RP each.

3: What is the cost-per-unlock for silver packs?
I only opened 2 blue backs because they're expensive. We need more data here. Each of the packs I opened had only 800 RP worth of items within. If we pretend that's the norm (remember, n=2 here so maybe y'all can help out), that means each blue pack really costs 4200 RP, making each unlock cost 2100 RP.

First conclusion: bronze packs are a good buy so you can unlock common permanent unlocks.
Since each can only be unlocked once, getting them out of the way means you'll unlock fewer common items and more uncommon/rare items when you move on to silver packs later.

4: Does our decision change if we're NOT selling all the unlocks?
Without selling the packs, the cost-per-unlock is (1250 * 3) / 2 = 1875 RP per common unlock. But the cost for silver packs is just 5000 / 2 = 2500 per unlock (common, uncommon, or rare).

5: Future directions.
It would be nice to know the distribution of rarities in silver packs. If you're more likely to get an uncommon or rare unlock than you are to get a common, then perhaps these packs are a better value. However, there's nothing in the game to indicate that, and I've already unlocked tons of common unlocks (basic weapon, basic vehicle, etc) from silver packs.