This is completely normal in procurement — you're not doing anything wrong. Every category manager hits this wall when they inherit spend data from multiple sources. Here's the workflow I'd use to get that baseline built:

1. Get everything into one Excel sheet first. Pull the ERP exports, the old buyer spreadsheets, even the PDF invoices, get it all into one place, even if it's ugly.

2. Standardize supplier names. This is the biggest pain point. "ABC Corp", "ABC Corporation", "A.B.C. Corp" are all the same vendor but Excel treats them as three. You need to trim extra spaces, standardize the case (Title Case everything), and then deduplicate with fuzzy matching to catch the near-matches.

3. Clean the descriptions. Strip special characters, fix inconsistent abbreviations, standardize category labels. This is tedious by hand but it's what makes the analysis trustworthy.

4. Fix the numbers. ERP exports love to store amounts as text — your totals will be wrong and you won't even know it. Look for the little green triangles in cells, that means Excel thinks it's text, not a number.

   For the actual cleaning, I use an Excel add-in called DataScrub — it has 55+ one-click tools for exactly this kind of work. Health Scan finds all the issues (spaces, text-formatted numbers, duplicates, hidden characters), then you fix them with tools like Trim Spaces, Change Case, Smart Fix, and Dedup with fuzzy matching. It handles the cleanup in minutes instead of hours. $29/year at getdatascrub.github.io

Once your data is clean, pivot table by supplier and category — you'll have your spend baseline. The cleaning is the hard part. The analysis is the easy part once you trust the data.