Price ranges for T61p, W500, and W510?

[thePCxp]

I'm looking to retire my T60 as my main computer later this year and I would like to replace it with a T61p, W500, or W510 (I would love to buy a brand new W520 but its too expensive for me to buy a brand new ThinkPad right now). I was wondering, how much should I expect to spend for each of those ThinkPads here in the forums? I've been doing some research lately and I seem to have an idea but I want to get a second opinion, as I'm not completely sure.