This gateway is sponsored by the Deutsche Zentralbibliothek für Wirtschaftswissenschaften (ZBW) - Leibniz-Informationszentrum Wirtschaft. The gateway is maintained by me, Thomas Krichel. I recommend you use the AMF metadata format to get the most information out of the OAI and RePEc.
OAI-PMH is a cumbersome protocol. If you use RePEc data on a regular basis, I strongly recommend getting in touch with me via email to krichel at openlib org or via Skype to thomaskrichel, to set up an ssh-based rsync solution. This will be much more efficient.
Another way to get to this data is to mirror it from ftp://ftp.repec.org ftp archive. It contain almost all RePEc data, well, at least those that I think are useful to others.
If you insist on using OAI-PMH, you can use OAIrepecSeries.pl. It was first drafted by me and then improved by Christopher F. Baum.
Good luck, and cheers!