I'd say this:
It's great that you're trying to grab some domains that you believe have value, but I think you should be researching more before doing so.
Always look for some important points before hand regging a .com
1- Make sure it consists of good keywords within the phrase, try to avoid "helpful, nice, perfect etc." description words as prefixes, unless they make perfect sense.
2- Check their CPC and SERPS, look if there are sponsored ads when searching Google for your "Keyword Keyword2". usually its a good indication.
3- If other extensions are regged, then most probably you got lucky and this domain does have some value even if you dont perfectly know it.
4- Think about a development Idea! What would a buyer put on that domain?
5- Search previous sales! Estibot.com would show you similar previous sales that would give you an idea, DNSalePrice.com and NameBio.com are two good places for that purpose as well.
6- Check the SERPs numbers, the higher the number of results with the exact match, the higher the chance that this term is good, always use quotes before and after your term.
7- Most important, does it sound right to you?
I am sorry about such a long post, but i was just intending to give you an idea about picking a good domain if you insist on buying an available .com and at the same time, I didnt want to take you down by just throwing "This domain has NO VALUE" at your face.
~Rami