Yes, 700 is the modern wheel size, and it does not matter for tubes. It does matter on tires. Google is your friend.
http://www.bikeforums.net/showthread...700-vs-27-inch
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Please don't confuse ebay "asking" prices with "selling" prices. Many sellers never get their ask price. some are far from it. Value is determined once an item actually SELLS. Its easy enough to check SOLD prices.