There are many sites that you can sign up with that will mail you coupons and samples. Here are some that I found very helpful:
The sites above sent me some sample sized cans of formula as well as single serve formula packages. Along with the formula they sent me coupons to use in store. These coupons varied in value but they helped out specially when stores such as Target and Babies R Us had sales.
Other sites that helped me out to get samples and know more about products were:
The bump box is mainly for mothers but do have some baby items as well. They have different types of boxes to choose from. I got a sample box that they were having deals on which you can always keep an eye out for their promotions so you can get the less expensive box. This box would have lactation cookies, organic lotions, hand sanitizer, salt for you feet, sunscreen, etc. They were all sample/trial size items but for the cost I was able to try out new products.
The target box has not been available for too long but as soon as I found out about it I was on it. I paid shipping for it and it was well worth it. This box came with a travel size of wipes, Honest hand sanitizer spray, lotion, Dove baby wash, and much more, all for only the shipping cost.
Wal-Mart boxes come to you during pregnancy, one every trimester. This is one you may want to subscribe as soon as you become pregnant in order to be able to take the full advantage of what it offers. The box in the picture was the most recent box they sent me now that my son is 1 year old.