IMO
- w4f.com - Mid to High $xxx , it is a future investment and i think you can find many people that would pay high $xxx for a 3 letters .com
- stx.net - Low $xxxx (i guess not more than $1500-2000). You know, the problem is the "x". But anyway you can earn some good money (even if it depends on how much you've paid it)
- gdjp.com - High $xx to Low $xxx - But as VegasFD has told you, hold this domain, 4 letters .com's are increasing their value day by day. I'm pretty sure there will be no less than $100-150 sales within 2009.