It's strongly suggested that you avoid using Master Documents--see these
links for why:

Why Master Documents corrupt
http://www.mvps.org/word/FAQs/General/WhyMasterDocsCorrupt.htm

How to recover a Master Document
http://www.mvps.org/word/FAQs/General/RecoverMasterDocs.htm

http://www.addbalance.com/word/masterdocuments.htm

However, Word will easily handle 200 pages in a single document.

Here is one method to do what you want:

Use Insert File to combine the documents. You will want to put section
breaks between each document. Each section by default is formatted as Same
as Previous, leave it that way.

In the footer, you want to have Page {PAGE} of {SECTIONPAGES}.  The words
enclosed in {} are Fields--you can type in the name of the field, but you
have to insert the {} by hitting cntl-F9.  Or you can insert any field and
then change the name of it, click shift-F9 to display the field code instead
of the field result.

Since Same as Previous is on, this will put the above field in all your
footers. You can turn Same as Previous off once you have done everything
that applies to all sections, if you also have formatting that varies.

Then you need to set page numbers to start at 1--on the Header/Footer
toolbar, click the [#hand] icon to Format Page Number.  Sadly, Same as
Previous will not carry over for page numbers, so you will have to do this
for each section.

Hope that helps,
DM