One of the things that buyers look for in a high quality watch is a "sapphire" crystal.  A synthetic sapphire crystal is the hardest and most scratch resistant material for watch crystals.  Most watches less than $100 will NOT have a sapphire crystal.  Unless you get an extremely good bargin you can bet that that sub $100 watch does not have a sapphire crystal even if it was advertised as such.  A few watches can be found between $100 and $200 that do have sapphire crystals.  If it's a good watch that would be a great bargain.

BEWARE that many dealers either do not know the difference between a regular mineral crystal and a sapphire crystal or they don't mind misleading buyers into thinking a watch has a sapphire crystal.  I recommend you check with the manufacturer or a reliable source as to whether or not the watch really has a sapphire crystal.

jamesinnc