In this article, admins have communicated that game discounts will be active between January 11th (Wednesday) and January 14th (Saturday). 25% discounts will be available ONLY for existing Workout areas and companies. There will be NO discount for the new Workout area (to train new intelligence skill) and for the new naval battles related companies.

So, what will you be able to buy? We can try to guess, given the current costs of existing similar buildings.

Existing skill workout areas, to train Strength
Q1: free
Q2: 15 gold to upgrade (total 15)
Q3: 52.5 gold to upgrade (total 67.5)
Q4: 127.5 gold to upgrade (total 195)

New skill workout area, to train Intelligence
Q1: free
Q2: 20 gold to upgrade (total 20)
Q3: 70 gold to upgrade (total 90)
Q4: 170 gold to upgrade (total 260)

Existing materials raw factories (Grain/Food raw, Iron/Weapons raw, and Sand/Houses raw)
Q1: 375 USD (around 1.87 gold)
Q2: 750 USD (around 3.75 gold)
Q3: 7.5 gold
Q4: 2250 USD (around 11.25 gold)
Q5: 26.25 gold

New material raw factories (Ship material)
Q1: 500 USD (around 2.5 gold)
Q2: 1000 USD (around 5 gold)
Q3: 10 gold
Q4: 3000 USD (around 15 gold)
Q5: 30 gold

Existing finished products companies (guns, tanks, helis, houses, hospitals, defense systems)
Q1: 7.5 gold
Q2: 15 gold to upgrade (22.5 total)
Q3: 52.5 gold to upgrade (75 total)
Q4: 127.5 gold to upgrade (202.5 total)
Q5: 277.5 gold to upgrade (480 total)
Note: To buy a tank company, you need to have a q5 gun company. To buy a q5 heli company, you need to have a q5 tank company. So, for example, if you want a heli q3 company you need to spend 480 gold for a q5 gun + 480 gold for a q5 tank + 75 for a q3 heli (total 1035 gold).

New finished product company (warships)
Q1: 10 gold
Q2: 20 gold to upgrade (30 total)
Q3: 70 gold to upgrade (100 total)
Q4: 170 gold to upgrade (270 total)
Q5: 370 gold to upgrade (640 total)

Warehouse upgrade
Normal (+1000 items capacity): 1312.5 USD (around 6.56 gold)
Big (+9000 items capacity): 26.25 gold

My personal (but generic) suggestion to new players is to follow these priorities:
1 - Intelligence workout area: everybody starts from 0, so there will be no big difference with old players in naval battles.
2 - Strenght workout area: land battles will still be more frequent and important.
3 - Existing raw factories: Sand/Houses raw if you want to sell in the market and easily gain USD. Food/weapon raw factories if you want to produce finished products to sell or use.
4 - Warehouse upgrade: you absolutely need it to store raw materials if you want to invest in finished product companies.
5 - Existing finished product companies: it's really your choice to select which one. What the other players will buy and upgrade is almost unpredictable, so I don't want to suggest something that may have lower value after the updates.
6 - New raw and weapon companies: they will have a brand new market with no previously existing companies... but remember that
- they will cost more (no discounts)
- we don't know yet where the new resources (and related production bonuses) will be placed
- we still don't know how many naval battles will be used worldwide and in our country
- older/richer players will surely invest in these new opportunity, so you will have rich competitors.
So my suggestion to new players is to wait for the next discounts (a couple of months) to invest in the new companies, and see how much the new market and warfare will request these items.

Also, remember that next weekend everybody will gain double energy/minute. This will be important expecially on Saturday, last day of the discounts, to try to gain a few more golds while fighting for your country...

Enjoy your shopping!