The squatter has several names registered, has indicated to me that my particular name of interest is for sale, and he asked me to give him the best possible price. I said $300, and I never heard back from him. If I want to use the name, do you have any suggestions?

    I said $300, and I never heard back from him.
    If I want to use the name, do you have any suggestions?

Bid more than $300?

If you don't know how much the domain is worth, you should do some homework. Here are a couple of sites I've used when attempting to determine the market value of a domain:

http://www.domaintools.com/buy/sales-history/

http://www.domain-prices.com/search/prices/5000

I have tried those services. They never give me any info - you see, nobody has ever used that name before.

Is there a way to see how long he has owned the domain? From there, estimate a yearly cost to him (12$ * years registered) + 10% profit and start from there. That seems reasonable.

You can use whois to see when the domain was registered. Since all the other extensions weren't registered I'd assume this is more of a brand style name and was registered fairly recently. It is hard to assign value of a domain without knowing what it is. Also, most people who sell domains are looking for the sales to compensate for the rest of their portfolio that don't sell. So registration fees + 10% wouldn't likely work as an offer.

The economics of owning a lot of domains pays off when your portfolio covers the cost of all registrations/renewals. The average churn rate on big portfolios is 2-3%. So simply offering a 10% on top as profit doesn't work. The average sale price is ~$2000.