I've been looking for an affordable one for years. They're not very common on eBay anymore. I'm looking for the later version that came with the mp15 engine that had the horn and I believe it had a switch to switch from parallel to series running.
The $150 set on eBay is the one first version without the horn.
IMO $150 plus shipping is steep for what they're offering. Basically you're getting a powered unit, three cars, and an unpowered unit...