fuck me, one calliper has fallen off and the other is barely hanging on!! your lucky to be alive and whoever worked on the brakes last (i'm guessing previous owner) should be shot!

i got my callipers and hubs for £100 off ebay which was cheap at the time. don't know what they go for now but i wouldnt expect to pay more than £200 for used items. i'd be fitting new discs and pads at the same time. mine came with dics and pads that were advertised as worn but fine...they were fucked imho. also, sounds like one of your flexi hoses has ripped off (with one calliper doing a dissapearing act) and the other one will have been stressed so get a set of braided flexi hoses front and rear for it too. they will be upt £65 ish for a set. cheaper if you have rear drums.