I have two 1 year old but never dived and still in the factory bubble wrap Kiss GEM rebreathers for sale. These are gas extenders that strap on the side of a normal scuba tank providing 3x the run time. Due to their 18 lbs travel weight, and because pure O2 is un-necessary, I think this is a great travel tool for long dives.
A video overview is here:
A three day training course is mandatory, but wetpixel members Doug Ebersole and Walt Stearns are both fantastic GEM instructors. No O2 sensors or scrubber cartridges are included with these rebreathers.
Both rebreathers come with a Zeagle wing and harness.
Prices:
1. Kiss Gem Full Kit with Single Jetsam PO2 Display, $2500
2. Kiss Gem Full Kit with Fischer Cable, $2600
3. Shearwater Pursuit OC/CCR Fully Unlocked Trimix Computer with PO2 Monitoring, $800
If 2&3 are purchased together, I'll bundle them for $3300.