Does anyone happen to know the original retail cost of the Axiom AX500a sub-woofer? (400w 10" sub).

The only info i can find is through the vintage link :

but that doesn't list pricing.

I have one, but i think i'm going to upgrade to a newer one so i'll be looking to sell the AX500a. I'm just trying to gauge how much it's worth now, and knowing the original price could help me work out a fair price.

Any ideas?