Divinity soul combo

Tomorrow in Wartune you can buy divinity souls, the gems you can use to enchant sylph gear. A level 1 gem cost 99 balens, and you need 4 to make a lvl 2, four of those to make a lvl 3 etc. They also immediately start a synthesise event, where you get a lvl 1 divinity soul for making a lv 2, a lvl 2 for making a level 3, and a lvl 3 for making a level 4 (once per day each).


Looks like this event last only for 2 days, so there is not much room for a combo. You have the following options:

1.) Don't buy (always the easiest and wisests).

2.) Spend 400 balens on the first day to make a lvl 2 gem, and spend another 300 on day2 to make another level 2.
So you spent 700 balens, got 2 x lvl 2 gems, one lvl 1 gem, and can claim he smallest one-time goodie bag.

3.) Spend 400 balens on the first day to make a lvl 2 gem, and spend 1100 balens on the second day to make a lvl 3 gem. 
So you spent 1500 balens (actually 1300, if you have your 200 balen discount), got a level 3 and a level 2 gem, and can collect the second one-time bag.

4.) Spend 1500 balens on the first day to make a lvl 3 gem, On the second day, you spend 3900 balens, and make a lvl 4 gem.
This way you spent 5400 balens and got a level 4 and a level 3 gem and can collect the 4000+ and the 1000+ one-time goodie bag.

There is even option 5 where you make 2 level 4 gems, but I think even option 4 is too expensive. We gonna get plenty of these gems for free very soon. You wouldnt pay 5000 balens for a normal lvl 3 gem either, right?

Personally, I will choose option 3 so I can use the coupon.