@andrewcooke: There is an analogous situation to property taxes though -- Rezoning a property. If you can acquire land zoned for something cheaper like residential or agriculture and get the city to re-zone it to commercial it's almost always worth a lot more. Overnight the property is worth a lot more and the property taxes will jump, so you'll either need to get the money to develop it yourself or sell it off to a developer who can do so.

And as far as the cost of entry, there are countless fields where patents could only conceivably be filed by someone with a lot of capital: auto, aerospace, medical, pharma, etc. There are certainly lone inventors working in these spaces trying to file patents but it's unlikely they're working on stuff where you need access to enormous wind tunnels or a medical testing population.

EDIT TO ADD: And aren't we as software developers going on and on about how software patents are worth anything? The cost of entry isn't very high at all and therefore they'd be worthless. Patents were supposed to protect the little guy from losing his large up-front research and development costs to the big established guys.