Either they are $7(register fee) or over $1000? My startup uses a popular keyword so decent .com's are hard to find. Any ideas?
Just in the nature of the domain name business (and here isn't the place to discuss whether there should be such a thing), mostly you're going to find concentrations of premium domains, whose owners are perfectly happy to spend a few dollars a year holding on to their property in the hope of one day achieving a multi thousand dollar payout. So what's easy to find that's for sale is expensive; and what's not yet registered is all but free!
Finding that middle market takes more work, because really you're looking for domain names that aren't owned by people who make their money selling domain names, and where the use for the name has gone away. A significant proportion of all the domains ever registered and brought into service are in this category, but tracking one down that's right for you and where you can come to a good deal is likely to take more time and effort than the straightforward commercial dealings buying new registrations or domains advertised as for sale.
There are places you can find mid priced domains but it requires a bit more leg work (searching on a regular basis) than just finding a name on the first search.
I would trawl through the following sites for existing owned domains:
Or give up trying to buy an existing name and try and generate your own, the following domain generator site is pretty good for quick searches: