How much are these old pc's worth?

Ok i moved in when with my sister over a year ago,she asked me if i had an extra computer she could use,and mabye 2 more for her kids, i told her that i could put 3 together for extra parts i had lying around.

Well i don't plan on living with her for ever,and she talks like the pc's is hers and her kids,and like i gave them to them,i don't mind letting them use them until i move,but i will not just give them away.

When i do move out,if she gets upset about me taking them i will tell her she can have them if she pays me for them.

I was hoping you guys could help me find out what they are worth.

 

The pc's are:

PC1:

Ultra E-Torque ATX Mid-Tower Case

XFX nForce 680i LT SLI 

EVGA GeForce GTX 460 SE :$ 119

Western Digital 320GB IDE 7200rpm  

Ultra X-Pro 600w SLI Ready :$ 130

Intel(R) Core(TM)2 Quad Q9450

Hyper 212+

2x2GB Patriot Viper DDR2 1066MHz

PC2:

Unknown ATX case

Abit kn9 sli

AMD 5600+ AM2

2x2gb ddr2 667mhz

120GB ide drive

1GB GT240

480w psu

PC3:

eMachines stock case and mobo

Amd 3400+ socket 939

4x1GB ddr ram

320mb 8800GTS

120GB IDE drive

480w psu

 

All 3 pc's have DVD-RW drives.

Thank you guys so much for the help.

 

I hope i put this in the right place,cause i was not sure where to put it, i am sorry if i did not.

PC1 - about 150 - 180 (you could almost get that though for just the cpu & ram on ebay.. well here in oz anyway)

PC2 & 3 - 50 to 70 would be fair - perfect linux boxes.