Are they just stuck to the spark plug? Have you tried twisting and pulling?
If they are still stuck, try a shot of PB blaster down the boot and pull it up with a string around the boot.
If all else fails, let the PB blaster soak, then shoot compressed air right down and it should come up.
Here is a pretty recent thread on the topic.
http://forum.planetisuzoo.com/viewtopic.php?t=49735
As for replacement boots, I would just replace them for the hell of it. I got them for $6 each or less.
The #6 boot is shorter than the rest so do mix it up. I bought AC Delco boots and they look like just like OEM, same part numbers too.
BTW.. Welcome!