When I knew I was going to dive, it was a no brainer for me - it was all about the $$$.
Here's how I look at it. Most ops rent either a set of full gear or a la carte - did a quick look at 2 top ops in Cozumel. One does full gear for $37.00 and both do individual items for $10/apiece - these rates are usually for the day (as opposed to per dive.)
Before I replaced my BC, I had 128 dives with it so I'll use that number for the reg and wetsuit (rather full or shorty) also. For the example, I'll say that total was for 64 boat trips of 2 dives each. I paid $1398 for my BC, reg, 3mm, and shorty. Renting just those 3 pieces of gear at $10 per item for 64 boat trips would total $1920. Could do the same thing with other pieces of gear such as fins. My dive computer past and present took more and will take more dives to make it cost efficient. In the long run, even with servicing, you'll come out ahead.