Good Point
When I got my fist set up I started with the BC b/c of my LDS recomendations. I used it with rental reg,octos and gauges for several years be for buying my reg. Now I've gone through two sets for Regs and still have the same scuba pro jacket bc. Good thing I like the jacket style like previously mentioned.
Today, if I was just starting out I'd get the Reg Octo and gauges first b/c I dont like putting my mouth on other peoples rigs. Here in FL some dive boats require at least one diver in a pair to have a computer.
I'd start with a pistion style first stage scubapro R190, a Oceanic Alpha 8, sherwood brut/magnum, Zeagle Envoy ReZort, etc. Get the cheapest octo you can find new with a warranty of course and spend the rest on a computer. Then by the BC and continue to upgrade from there until your happy. And like most on these equipment threads you'll always want to be upgrading to meet your personal taste.
I don't think its a bad idea to buy gear early in your scuba venture. Most of the time the cheapest gear new gear of your own is much better and more compfortable then any rentals.
Also, like someone else mentioned 99% of the time you rent the will not break up the gauges and octo, so forget that thought.