you can get very reasonable quality,
decent sounding far eastern made mandolins
for much less than £100 if you know what to look for
and shop around..

they're certainly not crap
and plenty good enough for beginners and experienced players..

heres a starter.. a very good to deal with ebay seller
who specialises in good quality 'budget price' mandos

http://search.ebay.co.uk/_W0QQfgtpZ1QQfrppZ50QQsassZsafetywoman67