The best way to answer this question is to look at how much people spend on average on their engagement rings as compared to their wedding bands. The national average cost for an engagement ring was $5,855 in 2014. The national average cost for wedding bands were a little different, in that couples spent an average of $1,417 on the bride's band and an average of $558 on the groom's band, which adds up to an average of $1,975 for both of the wedding bands. So, if you go by the national average cost of wedding bands and engagement rings, you can expect to spend about 33.7% (or just about 1/3) of what you spent on your engagement ring on your wedding bands.