kbmasOn,

To answer your question, yes you need to know exactly what you need when you order from buycabinets.com. Basicly you need to have your cabinet layout done first, and simply give them a list of cabinets and all material you will need(including filers, moldings...) and get a quote from them. In general fillers are used in two places: To fill up the gaps between cabs and cabs/walls 3 inches or less(you or your installer may need to trim it when installing), or seperate doors/drawers which will be too close otherwise (ie, around a corner)

For the cabinets and material models and specs, you may download a big pdf file from their website (for Somersby it's a 400+ pages document). It provides very detailed info including list prices (The actual prices I got from quotes are around 30% of the list prices) for each item. It is very helpful in designing your kitchen, because not only you know what cabinets/material to choose from, but also how much each option will cost so you can make better decision. For example, you can find out a "super susan" cost almost $1000 , but a "lazy susan" option cost less than $600 (I got one of each of them)

Just my two cents and hope it help. Now our kithen is 90% done and we love the cabinets!