The numbers might need some adjustment after experiencing the program in operation, but I'd think that a refurb discount averaging about 30% with an allowance to the owner doing the trade-up averaging about 50% should work well and make a complete program when added to the 10% Factory Outlet and 5% five item allowances.
Call me a cheap bugger, but I would be looking at $50% off new as a starting point, + a bit of a premium for the warranty, maybe 10%.
Do you differentiate between something less than a year old and something 4 years old? How about V1 vs V2 vs V3? I would view V1 as having almost no trade in or resale value.
Thinking more, 30% off on a pair of V3 speakers not more than a year old with the balance of the warranty would feel like a good deal to me.
Just random thoughts...
