Just avoid SLS for non-computer electronics man (erm with some exceptions like OP?). Every SG forums should have this as login message. They are simply not interested in selling anyone cheaply. More keen in chopping. If made to sell cheaply they will just try funny stunts like taking away the batteries. If you kena, take out the manual from the box and show them that it says batteries included.
Try asking a shop the price of some item, then walk away. Come back and ask for the item again. Good chance he'll tell you he scold you for going off, give snide remarks, say he just sold the last set, then try to sell you something more expensive.
Equipment: a pair of cranky spectacles with scratched lens :dunno: