A huge expense with any infant are diapers. Be prepared to fork over the money for diapers. If you talk to different people out there they will swear by Huggies or Pampers. Its all a marketing scheme. I have found that what works best for us are the Target brand. They are cheap and often times come with gift cards (which help to offset the cost).
You have to watch for the deals and then stock up on them. The picture above has a $10 gift card when you purchase 2 of the giant packs. I wait until I see the $20 gift card with purchase of 2 giant packs. Sometimes there will be a $30 gift card.
A very popular diaper deal among parents is the Amazon Family Subscribe and Save. By signing up you save 20% on name brand diapers if you have them shipped on a monthly basis. Honestly I think that is a waste. If you are savings minded you can find the deals on your own and save just as much if not more. I thought about that but it was too much of a pain for me. the best deal was the Target diapers.
Now another question people have about the knock off brand like Target is the quality. Let me just say this for the Target Brand. As I write this Mario is now 18 months old (yes I am trying to play catch up with his blog). In his 18 months of using the Target brand there was one maybe 2 times where the diaper spilled out during the night. That is not bad at all. These diapers have been very reliable for us.
Now keep in mind that every baby is different. Mario was just barely 4 lbs when he was born. He is now 18 months and still wearing size 3 diapers. He was in size 2 for quite awhile but even longer for size 3. I believe size 3 are up to 28lbs. Last doctors visit about 1.5 months ago he was just 20 lbs. We are ready to make the switch to size 4 very soon.
The deal website that I check on a daily basis is: SlickDeals