Here is my advice based on my personal experience pumping breastmilk for twin boys for a full year. Of the 12 months I supplemented with formula for about 5 of them.
Your little one is only 2 weeks old so you have a bit of time before you have to worry about it. Your wifes supply will change quite a bit over the next few months. There is a good chance that she will make more than enough milk and still have extra to freeze.
Your wife should continue pumping as long as she can.
I found that when I went back to work it was actually easier since I was on a very strict and regular schedule.
Don't be afraid to mix formula. (Unless your wife is going back to work soon, I would hold off until your little one is at least a month old.)
What I did when going back to work was to add an ounce of formula to each bottle through out the day and then at the end of the day freeze whatever milk was left in the fridge. It helped me to set up a nice freezer supply gradually over time.
Spend the extra money and buy the small 8oz bottles of formula
Because your little one is getting primarily breastmilk they won't use very much formula. Powdered formula expires about a month after it has been opened. I spent extra money and got a case of the 8oz travel bottles of Similac formula. It ended up saving me a ton of money in the long run. One thing to be careful of is to try the brand of formula you want to use first to make sure the the little one won't react to it.
Buy extra storage bottles for the fridge.
I used a Medela pump and bought a total of 9 storage bottles for it. It allowed me to use them to store and transport the milk without having to wash bottles constantly. I only used the milk storage bags for freezing.