I have to agree with mdwest. There is no possible way you are going to fit 500 sticks in an 18 bottle cooler. I have a just over 400 sticks in my 32 bottle cooler and I'm almost out of space. I use boxes to store my sticks, and it works fine. I like using the boxes because I can store certain brands in certain boxes so i know where everything is. Then, when you need to rearrange the boxes to make more room your not always handling the cigars. just my .02 on that.
Before you buy at Lowes, check Craigslist, you can usually get a great deal on a wine cooler. You will spend the same price for a bigger unit as the brand new unit your looking at at Lowes.
Good luck in your search. Just remember, always buy bigger than what you need. Your going to fill it eventually anyway.