Now is a great time to buy (and the 4G iPods are great buys), so go right ahead.
As for the concerns expressed by iPodlounge, let's just say they're on an iPod Witch Hunt. The "audio problem" they claim to have found in tons of new iPods isn't really a problem, it's a "problem," something that could cause a really minor annoyance if you do a series of things to trigger the "problem."
<classy dramatization>
"Hey, if I do this, my iPod makes a noise!"
"Hey, my iPod makes noises!"
"So does mine!"
"Oh my gosh! My iPod clicks! Me too! Me too!"
"BURN THE WITCH!!"
</classy dramatization>
iPodlounge is a great website for all sorts of really great iPod information, reviews, and discussions, but they're obsessive in finding things wrong with the iPod.