I bought mine from Ebay for $10 also. It shipped on the 6th, but I've not received it yet. Let me know how it goes.
I've found that when you put them on, start at one end and slowly roll it down onto the device, making sure you don't get air or soap bubbles under the skin. If you do I just pull it back up and re-apply it.
Keep your fingers wet as this will keep finger prints off of it. You can removed and reapply as many times as you want. If you get frustrated, just set it aside and come back in an hour or a day later and retry it. It will be fine to let it dry off the device.
If you have to bend around an edge you might need to wait 5 minutes before getting it to stay bent so be patient. It's not super glue
I also second the idea of trying it out first with the one that came with the phone.
dave