Why are you looking for a WMS? What you should be going for is an ERP, with a wms module.
What's your budget? If you're looking for dirt cheap, I have one account that during start up stages used OFBiz from apache (it's free/open source.) I personally haven't used it or interacted with it, but anything backed by apache and that's free is worth the shot. http://ofbiz.apache.org