Facebook selling sites are the bane of my life...
Every single person who has responded to my most recent ad has offered well below the asking price - and think because they are offering it in cash(?!) it is a good deal ?
Eg.
Them : is this available?
Me: yes
Them: what’s the lowest you’ll go
Me : £600 as stated in advert
Them: I’ll give you £450 cash
Me: (???) 
The item I’m selling cost £850 and Iv only had a week. The place I bought it from doesn’t accept returns for these kinds of items (it’s not a mattress) plus the cost of shipping it back would be around £100 !
AIBU to tell these cheeky fucker time wasters to get fucked?!