Companion Voucher Question

[Guest_craig_*]

I'm not a regular Amtrak rider. Just the occasional trip from Washington-Union to New York-Penn. Anyway, I noticed a few Companion Vouchers for sale on ebay/Craigs List. I'm curious how easy these are to redeem, especially in relation to travel between Washington-Union and New York-Penn. Also, are they good for travel on Acela? I notice that there are some blackout dates, but I won't be traveling on those dates so that isn't a concern. I'm just looking to save a couple dollars on two round trip tickets.

Thanks for all your help in advance.