First, congratulations. Boys are awesome. I have two, ages 1 and 4. Here are my thoughts on your request:
*Crib (4 in one so it includes the changing table) - I don't know about 4 in 1 cribs but I would say that a crib that turns into a daybed or toddler bed would be worth the investment. But, if you are on a budget, IKEA makes great, simple, inexpensive cribs. And even though they are nice to have, you can do without a changing tables. Both my kids outgrew theirs by 6-8 months. If you get one, I would suggest you get one that can also be used as a dresser, etc. Otherwise you'll have this huge piece of furniture that you can't use for anything else.
*Stroller/car seat combo - Yep, a must have.
*Diaper Pail - Again, you don't necessarily have to have one. I did for baby one, didn't for baby two. I would recommend the Diaper Champ over the Diaper Genie. The former can use any garbage bag; the latter uses special bags (at least that's how it used to be).
*Hanging thing for above the crib - I suppose some crib 'ornament' is good for the baby, but rather than an overhead mobile I would suggest a 'peaceful planet' aquarium or the like. The baby gets more use out of it and as they get older they can turn it on and off themselves.
*Breast pump (where can I get an inexspensive one?) - Inexpensive breast pumps are handy but expensive ones are GOOD. If you don't want to buy an expensive one or can't get your office or group of friends to chip in and get you one, try renting a top of the line one from the hospital. A so-so pump will exasperate you; a good one is a lifesaver and a worthwhile investment, especially if you plan on going back to work. Generally they don't offer these at consignment stores because reselling voids the warranty, but you could try EBAY ...
*One of those things where you hold the baby in front of you - definitely try garage sales or consignment stores.
try once upon a child, a little behind, baby and beyond, bon ton's, bugs and bows, children's orchard, kids kloset, kidswap, purple pony and wee resell it
Good luck!