Array help needed :-(

Hi there everyone, I have a problem i'm trying to figure out but i'm not too good with arrays, just know the basics, if anyone could help me out on this it would be wonderful :-) I have two sets of data in columns of a MySQL DB, these items are size and price. Size is seperate by comma's in the first column, and I have it split into a dropdown box no problem to read (For example): small medium large but then I have a price field, which contains 1.99,2.99,3.99 etc ..... what I need to do is when someone selects an item from the dropdown - say small as an example, it would know how to get 1.99 from the price entry in the DB. I guess what I need to do is somehow associate each entry in the price field with those in the size, but I have no idea how to do it :-( Any help would be really appreciated as this stumps the hell out of me. Thanks Chris