Based on their account application, it looks like FDW requires a resale number and a Federal ID number in order to set up an account. The application also states "All accounts are COD, cash, COD company check for approved accounts only." and the web site notes "Low Minimum Orders". Interestingly, they also specifically ask applicants to list any relevant professional association memberships such as NSCA, InfoComm, CEDIA, etc. They make it pretty clear that if you are not a legitimate Contractor or Retailer, at least in the eyes of the relevant tax and business authorities, then Full Compass is the appropriate avenue for purchases.
One particular aspect to consider when purchasing from intermediaries like FDW or any other retailers/distributors is the transfer of warranty. Often, if you are not a direct dealer then you, not your client, are considered the final purchaser in regards to warranty. You may want to verify how, or even if, warranty can be transferred to your client.