If you use USB extensions past 15 feet, they should be active powered
extensions like the one from Best Buy, linked above. As for the $4
extension, I doubt it's active at that price. They say up to 75 feet
for daisy chained active "booster" extensions. I've heard that
before. For passive, 15 feet is max.
But yes, if you have to go more than 30 feet, at $20 typical for 15'
USB active extensions the cost adds up and I too would consider using
a wireless ethernet adapter and then running an ethernet cable to your
pc. You can go well over 300 feet of cable and can run up to four
off the same adapter.
Here's a good one:
http://www.provantage.com/buffalo-te...p~7BFLO025.htm
Steve