Something of a mix of missions there. Phoenix is the first of the Mars Scout program missions (every other opportunity - in the $400M ish range)

It takes the 'chassis' of the cancelled 2001 lander - but the instruments are mainly ones designed for the failed 1998 Mars Polar Lander. The instruments for the 2001 Lander ( called APEX.. Athena Precursor Experiment as a Mossbauer, Mini-TES and Pancam ) ended up as MER's Athena Payload .

Doug