is this a random collection of excel worksheets?
do these excel sheet have the same layout? (column order, data types, string lengths)?
do they have column headers in the first row, which are sufficient to identify that column of data and are these column headers unique enough to join similar data from all these sheets?
of course you could hope that running 200 proc import will provide coinsistent result data, but an obvious string column in one won't join up adequately with the same named column in other sheets when the others are empty or numeric.
good luck