Do you mean X45? I see folks selling used X45s on ebay, any opinions on what a fair price for a used one is?
The X45 is the older brother of the X52, which is the older brother of the X52 Pro. I believe the X52 has a couple more buttons (though I don't remember) and more rugged circuitry than the X45. Also, the X52 tends to destroy its cable connection between the two bases much less; the X52 bases connect with what resembles a PS/2 (old mouse/keyboard) connector whereas the X45 uses what looks like a serial connector which screws in. Yank on an X52 cable, it pops out no sweat. Yank on an X45 and it may just tear the connector off the chip.
I highly recommend buying a NEW X45 or X52 and a wall-powered USB hub(they're pretty cheap, can't see more than $10 or $15 for a very good one). These joysticks are VERY heavily power hungry to the point where I think they ought to come with a wall adapter. If you plug them into an onboard or "unpowered" USB slot, the PSU will strain, you'll experience spiking, and the stick will slowly die to undervoltage.
One other complaint that some people have (that I certainly don't share) is that the spring tension is very low. You can hold the base in your hands and jiggle it to get the stick to flop around. I enjoy that because of the way I fly, but others like stiffer springs. This is easily remedied by inserting rubber washers (with a notch cut out to get them around the shaft) or even a cut-up top of one of those CDR/DVDR spindle cases. Anything that shortens the spring will bring up tension.
A short note, I recommend not using the "SST" software that comes with it. It provides the same functionality as most games already do and only seems to cause problems. After you plug it in, I also recommend getting the updated drivers from Windows Update.
So long as you go through this little hassle to set her up right and the way you want in the beginning, they'll last you a long time, give you precise control, and take your hands entirely off the keyboard. The "wonder" of the X sticks is that the X and Y axis are hall effect sensors that use a magnetic field to measure deflection instead of the old standard mechanical potentiometers. Hall sensors don't wear out in any appreciable manner and don't drift.