OS X Lion is only supposed to cost US$29.99 to install on any Macs associated with your iTunes account. Some Lion buyers who purchased it through PayPal are seeing charges way higher than thirty bucks, however. Multiple users have reported the issue on Apple's support forums, and Lion buyer John Christman emailed us earlier today saying PayPal showed nearly $4000 in fees associated with Lion.
Apple support is now aware of the problem, and it's been classified as a "known issue" that they're looking into. Meanwhile, several affected customers are seeing their bank accounts significantly overdrawn, with all of the heinous additional bank fees that go along with that, so hopefully Apple also makes good on those additional fees.
If there's a lesson to draw from this, here it is: if you pay for iTunes purchases through PayPal, it's probably a good idea to switch to another payment method until this gets sorted out. If you haven't bought Lion yet and you're worried about paying 100 times more for it than you're supposed to, you can always pay for it with an iTunes gift card.