I always had the rule they if they can't afford the diamond, they can't afford to ask you to marry them.
Ha then I met my husband 

 poor a** broke as a joke.  We just wore matching James Avery silver bands for the longest time before we got married.  For both of them it was $100 max if I remember correctly.  We still wear them every now and then if we don't want to wear our good jewelry (like if we are going to Six Flags or something like that where we could lose them).  I also wore mine when my fingers swelled up like sausages the last pregnancy!