That's quite a lot of money to try to load onto a prepaid card and likely not something you'll find easily done.
Some options are:
With OKPay, you can reload using bitcoins, which OKPay will exchange into USDs for you (the cost of this was just reduced from 5% to 2.5% of transfered amount).
With AurumXChange, you can reload using USDs from Mt. Gox codes.
For that amount though you'll probably be best arranging trades with some buyers willing to exchange Moneypak to you. For instance, on the #bitcoin-otc there often times are traders looking for BTC and for larger amounts will go out and buy a MoneyPak to do the trade.
You can load a number of different prepaid cards with MoneyPak, up to $1,000 each. See the Prepaid Cards section for the list: https://www.moneypak.com/WhoAccepts.aspx
Along the same lines, you might find a trader that would deposit cash at Western Union to reload a Western Union prepaid card.