http://www.niagaracycle.com/categori...?sort=priceasc

I often buy parts from Niagara Cycle in New York state. Here is a selection of about 20 different 700C tubes with the schrader valve. I will not get started on a rant about presta vs schrader. Prices start under $3. I've tried all of the cheaper brands shown on the page. Can't remember if one brand turned out to be better than another.