I wouldn’t call £150 a “give it away” type of transaction. £150 is a lot of money to some people.
Say a bass had been for sale for 6 months for £300, and someone offered £150, that’s a perfectly fair offer considering it’s half of the asking price and lack there of a sale.
Personally, if you don’t ask, you don’t get. I’ve took losses on basses & guitars in the past and also made offers which have successfully been accepted.
My Fodera YYS was for sale at £3000 for nearing a year, sold for £2300 in the end. But if you want something sold, you have to compromise, all the idiots on eBay with basses for sale high above their price tag think they’ll get what they’re asking, but they wont. Which is why they stay for sale for two or three years until being withdrawn.