With orders of $25 or more, Amazon offers Prime members the Fisher-Price Thomas & Friends Thomas Adventures Space Mission Rover for $4.02 $4.52 with free shipping. That's the lowest price we could find by $4. It includes two moon rock pieces and features plastic connectors to attach Thomas to cargo cars or tenders (sold separately).

Note: This item is part of Amazon's "add-on" program and can only be purchased with orders of $25 or more.