I play things cautiously with this hobby. I didn't put any fish in for two months, and no corals for three and a half. Even then, I am adding them one at time (also partly for budgetary reasons), and with a few weeks in between. Hopefully your LFS is a locally owned shop, so if you paid more, maybe you can also feel good about supporting your local economy...
$5-$7 for LR isn't a bad deal as long as it is good quality rock. I got mine for a bit cheaper, but I was ready to pay more for better quality. It just wasn't around when I was ready to start up. Having poor quality LR will set your progress back by a bit...more die off, bigger ammonia spikes, possible bad hitchhikers and/or algae.
Always take your LFS with a grain of salt and research what you buy before actually doing it. That piece of advise (along with take things slowly) is the HARDEST advise to follow. It's easy to go into a shop, have something catch you eye, and convince yourself in a few minutes that you can't live without it...only to find out that it's incompatible with your tank, or that you paid too much...
Can't wait to see the tank progress!