Explosion.com is a good name. My feeling is low-mid XX,XXX for that. The .net to me is not worth much, since it is not the type of name to get type-in traffic, and any development of the .net would create free traffic for the dotcom.
Of course, having them both together creates a little more value for each. It is likely Explosion.com gets quite a bit of traffic. If that is the case, then it would add to it's value.
I wouldn't sell for less than 10K, though I would let it go for a little more than that. Mid XX,XXX to me would be a sell, unless the name does very well with PPC.