A smentoned above, there is not right or wrong way to go about this. Often it's down to personal preferences or finances at the time.
If you asked people to list the following items (BCD, Regs, and Dive computer) in priority to purchase order you'd get a number of permutations:
If you also calculated to cost of new equipment and its service cost over the time it would take to spend that money on equipment rentals - then equipment purchase doesn't make financial sense.
Of course we all buy our own gear, but we know it's not really saving our money.
All that aside: Decide on what you kinda want. Be it brand and price point and your budget and keep your eyes opened. Work out the MSRP total cost of all the items you want brought individually and then you have a max price.
I got a complete set, Regs, BCD, Mask fins boots as well as rash vests and board shorts etc in a flash sale (not as a bundel) which I knew would come (like the US black Friday). The price I paid for this mid range gear which I wanted soley for teaching in was less than I paid for one of my high end reg sets I use for fun diving
Bundles can be great, as long as you understand that you're not going to your total preferred set up - maybe some items won't be your favourite brand for instance. As long as you accept there will be compromise to your ideal expecations then all is good.
The more time you have to buy before you need to use the better chance you can make savings.
Me, I'm inpatient so end up paying the price at the time of deciding "I Want"