I bought 1250 card readers in china to give as samples in UK, must I declare on exit?

I bought 1250 card readers in china to give as samples in UK, must I declare on exit? What will the procedure
When exiting China and crossing to Hong Kong-must I declare the goods to the Chinese authorities? Must I pay customs? What will the procedure be? Can the goods be taken from me? The purchase value was about $1000-I have a valid receipt from the Chinese Factory, stamped and dated. I'm at wits end, as not even the Chinese factory can tell me what to expect at Chinese customs. Surely if you're taking commercial goods OUT of china-this is a good thing for their economy? Please advise.