They're about $220 new. Me personally, I'd rather go with something new, unless maybe you know the guy very well. Then that would be another story. Just my opinion. If this is for your Monte Carlo, then yes, an MSD box will be well worth it. What I like the most about these ignitions is that for a carburetor set-up, especially with the HolleyHP 4150's and the Dominators where you don't have a choke and you drive the vehicle in question on the street before the engine is fully warmed up, the Multiple Spark Discharge greatly diminishes and usually even eliminates the misfires, stalling, and the hesitations that would otherwise occur before the engine is fully warmed up. It creates a better idle, and w/out removing the choppy idle created by a long duration narrow LSA camshaft. So if it matters to you, you can still have that hi-perf sounding idle, but with a better running engine.