Worthy,
Unfortunately, value can only be assigned by what the market will bear, and right now I don't believe there is a market for .be, except maybe in Belgium.
Because the domain happens to be the single most valuable word in the english language, you might be able to nudge a little more value out of it, but it is still not going to be much. I would suggest developing it yourself or putting it away for a few years and seeing what the market looks like then.
As for libel.us, the same applies, only to a lesser extent. .us domains may be worth something someday, but not much today. Again, I think you would be wise to develop it or put it away for a few years.
As for your sales list, I don't think you could get $300 for it, much less $300,000. The domains are good, but the extensions are all wrong.
I highly suggest you spend some time reading old posts in the appraisal forum to get a good idea of how the appraisals work, then spend some time in the sales forum to see what domains actually go for. You might be a little shocked.
I wish you the best of luck. It's a tough business.