Are you using one of those bucket type infant car seats? You will need a bigger one at some point! You can get it now and start using it whenever. Some convertible car seats are actually good from birth (5 pounds) up and I know people who have skipped the bucket seat altogether. Those infant seats may seem convenient (until your back aches from carrying it!), but can cause babies to get a flat spot on the back of their heads and oxygen intake is restricted when sleeping in there. Just make sure you have a great sling or Ergo carrier to put baby in when you walk around. You want to minimize the time they spend in a car seat, it's way better for them to be attaced to a person and learn to see the world.
That is the second thing I suggest: an Ergo carrier. Look online. They are superior to the baby bjorn in every way and can be used until the child is 4 if you want! Also if you do not already own it, this is the best baby book ever: The Baby Book by Dr William Sears, go get a copy!
High chair will be useful soon, whenever you start feeding solids (usually after 6 mos). Excersaucer could be useful if you have the space, but not totally necessary. My little guy was crawling at that age so I think that is coming soon. Any toy that encourages a baby to reach out and go after it, rolling and moving ones are great. I like musical toys too. Baby Einstein makes some nice ones. Clothes, but think ahead.
I just looked at pictures to see what we got our son the year he was 6 mos old... stacking cups, teething toys, board books, tub toys, peek a blocks train and sorting blocks toy (where shapes go into the right hole in main cube, he could immediately put the blocks into the top hole and dump them out!), and I think we got a high chair then too.
If you are on a budget, try a resale shop or wait until March and check out the Pass It On sale! You can get tons of great deals on gently used things from clothes to strollers and save yourself a ton of money. You could wait until then to get a high chair or excersaucer or walker, there are always a ton of those and of course clothes galore. Get on the mailing list in the meantime! You can also sign up a a New Mom and get to shop the night before it opens to the public! http://www.passitonsales.com
HTH! Happy holidays!