Estibot is not a bad tool for checking some of the metrics like this one that you should be loking at:
Average Monthly Search Stats - [chilean red wines]
Average Monthly Searches: 57
Average Cost Per Click: $0.81 USD
Average Ad Competition: low
As far as the Estibot valuation, start by dividing by 10 and that is probably still best case end user value
What kind of sites are you putting up? Do you know how to drive traffic, or just think a developed site will automatically pull in traffic? How are you monetizing the sites?
Even if the value is in the site, the site still needs to be able to create revenue for the potential buyer. Do you know anything about chillean or fruity red wines that will allow you to intelligently create content for the sites? Is it a hobby or interest of yours? Are there products or affiliate programs you can use to earn money?
I could be wrong, but it just seems like you are pulling names out of a hat because they came up over $250 in Estibot - that's not a good criteria. Why not set some rules for yourself to make sure that the name has value before you even build the site?
1. No more than 2 words
2. Only .com
3. At least 250 exact match searches in Google Adwords Keyword tool
4. Something you know about
5. Estibot value of over $500
6. Average cost per click over $1.00
7. Advertiser competition medium or better
8. Name is a word or phrase in proper spoken order (i.e. pooltables not tablespool)
9. If spoken aloud, a person could easily understand and navigate to the site (i.e. not koolpewls4u.com )
10. Name is/was registered in lesser extensions.
If you create a list like the one above, you may not be able to find a lot of names that fit, but the ones you reg will have a much higher percentage of success. Besides, developing sites takes much more time than regging names does.