A few years back, Tim Meyers was advertising fully machined aluminum blocks for $3495. At that time the iron blocks were still in development. Don't know the prices today but I believe his phone still works.
Incidentally, his and Drag Boss's blocks are cast a lot thicker walled than Ford did so they can be bored MUCH bigger than stock. This makes them ideal for a 427 stroker Cleveland with improved oiling, if you want buckets of power that looks near-stock.