You can get various rewards from DNA expeditions, ranging from experience to dino dollars to DNA ambers. All having their own rarity.
Many people think the odds are very low but for me I have gotten these amber as cheap as just sending 5 buck expeditions in personal experience buying for 359 bucks is not worth it.
The most common rewards are experience: 100 XP, 250XP and 500XP.
The second most common rewards are coins: 2000, 5000 coins and 10,000 coins.
The third most common rewards are food: 1000 food, 5000 food and 10,000 food.
The fourth most common rewards are dino dollars: 1 dino dollar, 2 dino dollars and 5 dino dollars.
The fifth most common reward is DNA amber: 1 DNA amber.
The sixth and final most common reward is Limited edition DNA amber: 1 Limited edition DNA amber (usually on a Wednesday or three days over a weekend).
Usually do not waste bucks in AP and GP by paying for all three containers. Eventually, you will get the non-limited DNA in the first container- just have patience. However, when a limited DNA comes up in the second and third container you are offered the chance to buy it for 359 bucks. Think carefully - do you really want the animal? Check which limited animal is up for the expedition before opening the goodies - you can't check when it is offering you the opportunity to buy it.
A cheaper method of getting the limited DNA animal, especially on the 3 day offer, is to buy all three containers (for five bucks) and then hurry the expedition back after a couple of hours - cost is around 9 bucks to speed it up. Depending on the odds (in AP) I have got the DNA from between 5 to 8 expeditions. Even if it takes ten expeditions - 10 x 12 = 120. A third of the cost of paying the 359 bucks. Of course, if you really want the animal and have the bucks its "safer" to just buy it. You may just run out of time on the single day offers. Note: this works well in AP, but not in GP. I am sure in GP it reduces the odds of getting the limited DNA if you have paid the 5 bucks. You normally have to buy the limited DNA in GP for 359 bucks if you want it. I have done this twice hurrying back around 15 expeditions in GP and not got the DNA, and yet lo and behold send out the free expedition - and there's the DNA - do you want to buy it for 359 bucks?