buy瞬间动词,不能用完成时的!equipment是较大型的设备,instrument多指较精密的仪器fetch多指过去再按原路返回,如Fetch the doctor!把医生请来所以我的翻译是:We bought the instrument you required and all the cost is RMB 3000.Please come and take any time you are convenient.
您需要的仪器我们已经替您买到,费用为3000元人民币。 请您方便时来取。]Webought the equipment you need and it costs 3000 RMB. Please come and take it any convenient time.We have purchased for you the instrument that you need. The cost is RMB3,000yuan. Please come to get it at your convenience.