Basically, at the point at which you have to say "Well, maybe a domain could be developed as..." it's got virtually no value!
Pragmatically, the domain name has to stand on its own i.e. be self-explanatory and/or generic to have value.
The problem is that there is still the misconception floating around that "brandable" domains i.e. domains that with an expenditure of time and $$$ can be turned into a brand are valuable.
The snag is that at the point that a company has decided to make the commitment to expending that time and money to brand a domain, they are then free to choose ANY domain... and there are an almost infinite number of "brandable" domains still available!
Contrast this with a generic domain. If you owned "surfboards.com" then it's immediately clear what the domain can be used for, it's appealing to companies in the surfboard industry and it is genuinely unique - therefore justifying a decent valuation.
The other problem with brandable domains is that generally companies are either prepared to pay for a domain in the secondary market, or they're not. If they're not, the fact that a domain is being offered cheap won't help, since they're not even looking.
If they ARE prepared to pay for a domain, most companies will be willing to shell out a little more $ to get a good descriptive/generic domain since if they're going to have to put in a major branding effort they're going to apply their $ to the branding campaign rather than the domain.
All of the above is generalized and there are exceptions, but it's like winning the lottery - sure, somebody has to win, but it's almost never going to be YOU!
In the case of your domains, I can't see anyone offering you anything for them because they're not worth anything more than still-available names i.e. you haven't added any value by registering them.
