How about the price depends on how many names you have? That way the little guy can have his $7 domain but if you want to buy thousands of domains each successive one is more expensive and having millions of domains is prohibitive (as there is really no good reason to have them anyway).
That's a neat idea but might be a hassle to enforce, since people could use different registrars, etc. I really like the idea of making domains taxable like property, simply because the tax system already exists and is ruthlessly effective.
Combine that with, say, a price rise to $100/yr minimum charge per domain; that could include, say, hosting services or an ssh cert or something, the point is you cannot pay less than $100 per year per domain you own. That would hit the domainsquatting industry like a nuclear bomb.
