We consider tax liens as Federal or State Income Tax Liens or Special Assessment Liens which we include in our search.  But since they asked for liens, then yes they should pay for them.  We report deliquent taxes as a base amount, the total amount with penalty and interest, and a good until date.  We do not include tax bills unless the client request them and then we charge for them.  From your post, they did not ask for tax bills.  When in doubt always call the client to see if they will pay for them and write down the name of who you talked to, date and time, so you can reference it when invoicing stating they wanted the tax bills.
     We only send what copies our clients request, because why should they pay for copies they don't request?  And they won't pay for them.  If you only ordered a hamburger and a drink, why should you pay for fries you didn't ask for?  I can see you point about sending supporting documentation to help explain the taxes, but I am sure the worksheet you use can explain the taxes, unless you are having to train their employees, which is another post altogether.

Good luck,
     Jay