Whatever, best of luck with your sale, Its not worth starting arguing
I dunno if it's just that you aren't used to the forum, but it doesn't tend to be a case of 'get the best price' it works more like you state a price you want, someone offers to give you it, a sale is made, that's why it says you have to put a price, not just invite offers in an attempt to start a bidding war.
For what it's worth, your bass looks lovely, and I think £400 is a good price, but if you ask for that, and get offered that, then what more do you want?
Inviting higher offers is a different kettle of fish to giving it more time in case of a UK buyer.
(point still stands)