im looking for a value for money us site to look up bmd for a number of states
Unlikely to happen... There is no central repository for BMDs in US. Each state is responsible for its own vital statistics recordkeeping and they vary all over the place as to when they started doing so.
Costs seem to range $10-$20 and you need to know where death occurred (usually) and exact dates (nearly always); especially for such a common name as Robert Clark.
Plus, a huge number of indexes (if they exist as such) are not yet computerized. For example, I live within 200 miles of where my grandparents married, and know within a few months and miles when and where, but haven't found a marriage record.
Nick