For diploma, I only have one original Chinese government (issued by Osaka China Consulate many yeards ago when I was in Japan) certified diploma in my hand and I don't want to submit it use in Canada immigration, so I brought it with one Chinese one English copy of the diploma to a Chinese "gong zheng hang" in Mountain View, CA, asked him to submit a U.S. certified deploma and he did as my request(for him, no any risk as China government has already certified), it cost me $30(1st one cost $15 and 2nd one cost $10).
For tran, I think only need University or higher level I did like that, asked my relative in China, went to the Univ with my copy of transcritp several times and finally got it, cost RMB100 for each.