writing a manual

Hi, Sorry for the slightly off-topic post, but I've just had a client ask me to create a manual for the site management tool I wrote for them last fall. Since I've never had to do one before I'm a bit lost on what would be a reasonable amount to charge and whether or not I should put any restrictions on how many copies they receive or if I'm ok with them photocopying and handing them out all over the organization. Any thoughts on what a going rate for a manual is? The site management tool does what most content management scripts do - lets the client add/edit/remove any and all text on their site, upload pictures, upload and re-size pics for a photo gallery ... nothing ground breaking - standard PHP/MySQL stuff, though last time I tried to put a manual together it quickly got to be over 40 pages and that client decided they didn't want it in the end. Thanks -Tim