Three character .net's without meaning to them may be worth up to $20, but not much more because they are not particularly rare or in demand at this time. f04.net and n04.net are still available for registration, if someone wanted a similar name.
csdesigns.net and nukan.net are developable, though no obvious premium resale value.
xtream-mail.net contains (1) alternate spelling, (2) a hyphen, and (3) the .net extension. It only takes two of those qualities to make a bad domain. Let this one drop, please.