Finding an equilibrium between too low so that everyone can put all their garbage names out there and too high so that people with good names are scared off from paying the fee is virtually impossible. We as experienced domainers know what a good name is, and it's opinions like ours that will put only worthy names to auction. Even if the entry fee was $500 - the nutjob that owns some wacky 40 character hyphenated domain name with misspellings and seriously thinks it's worth $100,000,000 would still get that domain name into auction.