clustering continuous variables

[podarum]

Hi, I know you can't cluster by continuous variables, but looking for ways around it.. For example I have price1, price2 and price3  on a monthly intervals for the last 15 years of about 120 stores.  I want to cluster stores that have some sort of "something" in common between the 3 prices.  But do I look at average prices, avergae growth/loss, price growth in the last 5 years, slope, etc. or a combination .  Looking to see what makes most sense and which clustering procedure works best for this.  Thanks