I noticed rpmbuild (-bb and --buildroot options) creates the .rpm in different locations depending of what OS are you using:
Setting up the rpmbuild environment in /home/ http://www.linuxquestions.org/questions/linux-software-2/need-rpm-package-for-php-version-5-2-7-and-up-on-redhat-5-1-a-766486/#13
Actually it is not recommended to use /usr/src/**. I.e. by using /home/[name]/rpms/ you can work as unprivileged user. No su or sudo is required to build packages.