I'm looking into purchasng a new road bike after many hours on an old steel frame Centurion, which I love. I'm trying to find a reasonably priced Tiagra/105 bike with a 520 or equivalent steel frame.

The Mercier Corvus on ebay caught my eye. I emailed the seller, asking whether or not the rear derailleur is replaceable. She replied it was replaceable. After looking at the pictures further, it sure doesn't look like it. Does anyone have a steel Mercier Corvus or one they could look at to confirm this for me?

2nd question, unrelated: What are some other steel frame alternatives? I'd like to keep the price under $1000.