I'm going to disagree with some of the PP.
Baby bath: We have one that fits in the kitchen sink. We used it for DS (now 10) and are using it now with DD, which allows us to bathe baby while DS showers. It has a bottom drain plug, so there is no hassle to filling/draining it. We use the sponge inside of it, to keep baby from slipping. I don't like bathing a child in a full-size tub until they can sit up, it is REALLY hard on my back to do that. Now IMO what you don't need for baths are hooded towels and special washcloths; the ones you have will do fine, just wash them in unscented detergent. A baby bath is usually under $10 used; worth the convenience in my book.
Travel system: One word for these: EVIL! Where to start with this: usually the carseat is decent, but the stroller is a heavy, bulky steel piece of cr@p with no suspension whatsoever. Putting a child into an infant carseat in lieu of a stroller for long periods of time is hard on their backs and contributes to flattening of the back of the head, too. Little known truth: ANY stroller that has a napper bar can be used to carry an infant carseat, so if you need it in an airport, etc, then you can do it, but you really don't need a specially-matched set. Buy your stroller for the long term and invest, but pay attention to the model year and go for closeouts. A Peg Pliko is a really good long-term use stroller; Macs are wonderful, too, but not as comfy for new infants, and they don't have the aforementioned napper bar. (Which won't matter as much to you if you use a sling.) If you really feel you must have a travel system, the only one I know of that will also give you a really decent stroller for long-term use is a Chicco C10. Buy your stroller, carseats and high chair new, but buy them online, better selection and you don't have to pay tax.
Most babies outgrow the infant carseat by 8 months if not before, so don't over-invest in that one. (Infant seats are very convenient to have, but you don't HAVE to have one. If you get one, buy a safe seat, but the most expensive on the market is a waste of money given the short time you will use it.) Save your investment in this case for your toddler seats. Oh, and buy an infant carseat that can be used without the base; buying a second base is also a waste of money. We use a Baby Trend FlexLoc that was $70 from
WalMart online.
As far as carriers go, a sling is the most cost-effective. Carriers like Baby Bjorns, etc. are nice for little ones, but useless after about 8 months. A sling can be used as a hip carrier well into toddlerhood, especially at WDW. BTW, my DH simply cannot deal with using a sling; he can't get the hang of it for love or money, though he could use a front carrier.
I would buy your crib used; just be aware of the safety rules and recalls, including the possibiility of lead-containing paint. I don't think a convertible is necessary. A regular crib is fine as a toddler bed if you take off the sides and brace the legs underneath. (We used shower-curtain rods to brace ours, and it is now a crib again for DD.) You can buy chew guards to put on the rails when they are teething. You can get a bouncer and swing used, too; both are short-term use items if you want them.
One thing I find indispensable as a nursing mom who co-sleeps part of the night: a good swing-down bed rail for OUR bed. When I put baby on my right side to nurse, it protects against the possibility that she could fall out if I fall asleep. (She's fine between us on the other side.) Once she is independently sleeping in a twin bed the rail goes on it. Moving the bed against the wall would be cheaper, but won't work in our room because of the location of the door and closet, and besides, you usually can't get it close enough to the wall to be safe with an infant.
Check to see if you have a Once Upon a Child or Children's Orchard in your area. I buy almost all my kids' clothing at OUAC. Also, about gowns and swaddling blankets -- some kids love them but some hate them. Mine did. DD kept trapping her legs in the bottom of the gown and screaming to get loose, and both of them simply HATED being swaddled. I wouldn't take the tags off these until you know your child's temperament.
if you do, get a couple of good bras,well worth the expense- 
they just sort of moved from the'big bed' to a toddler set up when they grew.....
