Yes, BCD, regulator, wetsuit, computer, fins and torches are rentable on almost every boat, typically $15–40 per item per day or $120–250 per week.
Full rental sets are available on virtually every liveaboard, which makes flying with less luggage a genuine option. Typical rates are $25 to $40 a day for a BCD and regulator set, $15 to $25 for a wetsuit, $10 to $20 for a computer, and around $10 for a torch. Weekly packages usually land between $120 and $250.
What rental gear is like: mainstream, well-serviced and unremarkable — Scubapro, Aqualung, Mares and similar. It works, but it will not be tuned to you. The two items most worth owning are a mask, because fit is personal and a leaking mask ruins dives, and a dive computer, because you should know your own device's algorithm and alarms.
Reserve rental in advance rather than on arrival
Sizes run out, particularly small and extra-large wetsuits and BCDs, and remote boats cannot restock mid-trip. Give the operator your height, weight and shoe size when booking.
One caveat for cold or long dives: rental wetsuits are often thinner and more worn than the water temperature deserves. If your itinerary includes thermoclines, Socorro, Galápagos, the Sea of Cortez, southern Egypt in winter, bring your own suit or add a hooded vest.