Because this question is in the Category of "Air guns and Air rifles" and not in "Airsoft" or the "Paintball" category, I have to assume that you are asking about BB and pellet guns and not regular firearms.
The cheapest air/BB gun that I know of is the Marksman 1010C it's around $20. In fact most of the Marksman products are inexpensive. Then I would have to say the Daisy Red Ryder is next on the list. (Every kid I grew up with had one.) It sells for around $30. Personally I think the Marlin "Cowboy" model is nicer and cost around $40. If you are asking about Airsoft guns ( they shoot the larger plastic pellets.) Then place your question in the "Airsoft" Category.
used. check craigs list in your city. See link
Walmart
Walmart
If you mean what type of steel are guns made from, it depends. Some cheap guns aren't even made from steel, but instead some sort of cheap pot metal.
See the related links for cheap airsoft guns.
No.
Black List - L.A. Guns album - was created in 1985.
ebay
If you are looking for a list of cheap hotels in New York City, then you are in luck. There is a list of cheap hotels in New York City at www.Hotwire.com.
Places that have rented lazer tag guns are heavier than paintball guns. cheap plastic guns are lighter.
transparent Airsoft Guns don't really have a name. But people would refer to them as "Wal-Mart guns" or "Cheap Chinese Crap" since they are so low-end and the materials are very cheap.
I have two bookcases full of reference books- and THEY do not show ALL of the guns that have been made. There is no one list.