I'm ready to work for free.
Actually, i'm not :D I'm ready to work for $12/hour which is fairly low for a coder.
What draws my interest on your project is the low-budget thing. That suggests me that the hardware / VPS / whatever where this site has to run is low budget as well. This situation tends to rule out any PHP-based solution, for the reason that PHP is, in term of performance and resource consumption, the worst of all.
I can work on your website only if the target is at least an entry-level VPS (virtual private server). In other words, i need root shell access to the server. Also, it needs to be a linux box. Otherwise, my solution wouldn't work.
If these conditions are met, i propose a Perl-based back end, with mod_perl integration with the Apache web server, and, if necessary (but it usually is), an underlying MySql database with InnoDB engine. The front end would be pure HTML / CSS / Javascript with AJAX calls.
A site built that way runs blazingly fast and its resource consumption is minimal. But to be properly set up it requires the installation of some packages and the configuration of the web server, therefore it cannot work on a shared hosting. It needs root access to the machine involved and, by consequence, a VPS or more.