Thanks for your reply dnb8 but I think it's too late now: I haven't fixed the price and cannot start auctions because the offer was made through "SedoMLS GoDaddy" (I don't really understand why but I can't go against Sedo rules).
As you say with current offert I'll end up with 50 bucks
But I prefer 50% of 100 bucks than 100% of nothing
You will end up with $40 after sedo and the regfee. Do you do domaining for $40 bucks? If so take the money.
I would counter $500 (still low enough for you to hopefully keep this one important to you sale, but high enough for you to get a proper sale under your belt) and hope someone like 247media.com bidding.