Greetings Tresguey and you have been taught a valuable lesson about dive gear.
The next issue is to decide just how comfortable are you on working on your gear?
If you so choose o-ring kits are cheap, spare hoses are a good idea, computer batteries, spare time piece, extra SPG / spools, mask / mask strap, SS buckle, silicone lube, O2 compatible if you dive NITROX, fin straps if you have not went to spring straps yet, tools "multi dive tool", side cutters, adjustable wrench, quality wire ties, #36 line, Bungee chord, intertube of varying size, defog, extra RDP "tables", snaps, hose retainers, etc.
This is just a few off the top of my head but I have many more depending on the dive and proximity to dive shop. I have been able to save many dives not just for me but my buddies as well. I usually carry two of everything including regs, BC's, computers, hoses, wet suits, etc. I have only one DS for now but soon will have two of my own.
If I am going on a charter I will borrow a buddies as a back up.
It is just to easy to prepare for the worst and hope for the best.
I learned from my instructor and mentor MSDT Mark you can never be over prepared.
It has taken me several years to get to this point but it all started form having to set a dive out because of a o-ring! Never again!
CamG Keep diving....Keep training....Keep learning!