Well done on getting one up and working.
The fact there were bare wires hidden by the tape says a lot about the QC of the assembling company and some of the problems people have encountered.
BTW, in answer to your question re quantity/cost - usually minimum of 300 to 500 pieces, sometimes more and/or a minimum order cost of € 5k to 10k. That is for specific parts - circuit boards, non standard cables, ICs etc. If the parts are standard manufacturer jdec parts then we can usually get them at reasonable cost and numbers. It's the non-standard parts that cost.