Not sure about availability/cost, but here's a six-inch and Marvel Universe-scale Ultimate Spider-Man/Miles Morales.
UPDATE: The 3.75-inch Ultimate Spider-Man is a variant of the Spider-Man figure from the Marvel Universe line and should be available Spring 2012. The 6-inch Spidey is part of an upcoming Walmart-exclusive 6-inch Spider-Man line.
*Buy Marvel Legends figures at Amazon.