First, go to weightweenies.starbike.com and look at their listings. You can view old listings from the top menu of the first page without signing in. To sign in for the more recent weight contributions, you have to join and sign in and then find the listings spreadsheet link within the forums. But it's well worth it as you get hundreds, thousands of accurate, actual weights of all types of components.
That said, You can get alloy bars that are sub 220gm, but they are pretty rare. The Deda bars I think are considered pretty light, especially for the cost. Like Randy99CL said, you can get below 200 grams with carbon fiber, but I doubt if you'll find even used or closeout CF bars for less than $100, probably more like $200. Thats about as light as you'll get for any sense of reasonable cost.
A light stem, period, is a 100-110 gram alloy stem, and I doubt you'll get any lighter than probably 130 or so for the lightest you could find in your 120mm length. Just a guess but, again, I think Deda Newton is considered not bad weight-wise. OTOH, my 26.0, 105mm Syntace stem is only 105, but it's smaller and shorter than what you need. I think it's pretty unusual for CF stems to be lighter than the lightest alloy stems and they are $$$.
Your stuff isn't really heavy, but you might be able to save an ounce each if you do some educated EBaying using the weightweenies listings to guide you. It's fun as long as you don't get obsessed and waste money. Do the same for your seatpost and saddle if you want to play the game. (I enjoy it).
BUT.... Wheels, tires and tubes are the best way to lose significant weight. If you get wheels that are ~1400 grams (stripped bare of skewers and rim tape, just for reference) that would be a pretty much low weight alloy wheel. Yea, you can get lighter (Soul, Williams are two), but that's unusual for alloy. 1500 - 1600gm wheels which I currently ride, are not very expensive if you shop around, and are very nice an light in my opinion and probably not as fragile. A lot of basic, stock wheels are in the 1800 to 2000+ range so check what you have.
But tires and tubes - you can lose a lot of weight - 1/2 pound maybe - for cheap by going with high quality tires (like Michelin Pro Race) on sale and lightweight tubes.