keep the money in ur bank account for a month. if they ask for it back (which i doubt) u say "oooh i didn't know i'd been overpaid" pretend u didnt check ur payslip or u were expecting payment for sumfing. if after a month or 2 theyve sed nuffin then go and buy ur synth.
my gf gets overpaid all the time but its like a small nursery/ school care thing she works for and its alot easier to work out where their books r short than a massive company so she has to give it back.
if i was in ur situation id have a really good night out
