from :3character.com:
Current Observed Minimum Wholesale Price (regardless of letter combo) as of February 7, 2006:
3-Letter .com - $1850 (+ $200 since January 28, 2006 report)
3-Letter .net - $320 (+ $20 since January 28, 2006 report)
3-Letter .org - $130 (+ $15 since January 28, 2006 report)
3-Letter .info - $85 (+ $5 since January 28, 2006 report)
3-Letter .biz - $35
3-Letter .us - $25 (+ $10 since January 28, 2006 report)
The quality of the letter composition can play a significant role in determining 3-letter valuations. General concensus states that the letters A, B, C, D, E, F, G, H, I, L, M, N, O, P, R, S, T are considered premium letters. Other lesser high quality letters include: J, K, U, V, W. Lower quality letters include: Q, X, Y, Z. Domains selling for less than the above figures would represent a strong buy in today's market. Premium letter only domains tend to fetch a 500% to 600% premium (or more) over the Minimum Wholesale Price. Mixed letter quality domains have valuations somewhere in the middle of these two extremes.