I've had a brief look at prices and the costs seem pretty steep especially considering we are talking about a fairly old version of the OS.
I'm not sure what sort of prices you are seeing. But because OS 10.5 is the last OS version that is compatible with older Macintosh PPC hardware (which your iBook is)…the demand (and therefore price) remains higher for it.
What you have to realize is…OS 10.5 when it was originally released cost $129.99. Up until recently…OS 10.5 install disks on eBay were close to $100…and even more. It was mentioned earlier in this thread that an OS 10.5 disk could be had for $55.
So…$55 is certainly better than $100…and $55 is definitely better than $129.
If $55 is still too much (and you are currently running OS 10.3.9)…you could upgrade to OS 10.4. But…an OS 10.4 install disk is still going to cost you $25-$30 (maybe more)…so around $55 for OS 10.5 is really not that bad in comparison (considering that it is newer & more features than 10.4).
I'm thinking that there is simply a disconnect between what you thought an older OS should cost…and what it actually costs. If you had checked eBay first (to see what OS 10.5 disks were selling for)…then there would be no surprises or "sticker shock".
Another option is to purchase a newer Intel Mac (since your iBook is getting pretty darn old). The price Apple charges for OS installers for Intel Mac's are lower.
- Nick