First, they no longer put the dust boots on the struts, trust me i looked. You don't need them anyway. If you decide to keep your current struts just cut the remaining off with a knife. How did they shove the boot up into the body?
Yes, J30 struts are expensive, and so is having them replaced unless you can do it yourself. It is also likely that you need new struts although you do not realize it. Trust me, after replacing with new ones, you'll know just how bad they were/are. To check for blown shocks, pull off the wheels and look for moist spots around the top of the strut, right were the piston meets the hydraulic chamber. Also if you're getting oscillation or bounce in your ride or large dips and bumps make funny noises, it's about time.
You are also correct that your only choice is OEM tokico's. As far as the best place to purchase...people either purchase through,
http://www.infinitipartsusa.com or
http://www.infinitiparts.net. Wherever you go, it'll be cheaper then going to the dealer.
I would also go back to the place that changed your oil and get a better story. Were you there when it happened? I just can't see how jacking up a car would result in a damaged dust boot unless something REALLY bad happened.
good luck and let us know how it goes.