That's about right. You can spend days and days searching and only save yourself a couple dollars. But if you're so inclined, sometimes dealers do 603's on ebay for $50-60.
johndavidstuts, if your interested in a Marshall 603s mic, then I'm your guy. Let me know if your willing to spend at least $60-64 on it. I will set it up on ebay.
I literally only used it about 5 times! I had an acoustic guitar but returned it because it was too boomy and I didn't have any EQ to solve the problem.