We have made a preliminary comprehensive cost estimation for reliability of life support systems (LSS) in 1000-d remote space exploration missions with the loss-of-crew probability at 0.0001 due to failure of hybrid, partly and maximally closed-loop LSSs currently used onboard the ISS Russian segment. Comprehensive cost of a simplified test program is 5-times higher than cost of any LSS. A beta-factor parametric model was used to analyze LSS reliability against common cause failures (CCFs) when reiterative redundancy cannot provide superhigh reliability. It appears that the required reliability against CCFs is achievable on the diversification principle, i.e. reiterative diverse redundancy of basic LSS technologies. The estimated LSS cost is twice as much in comparison with the traditional approach that takes into account independent failures only. Diverse inherent cold redundancy can reduce the cost about 30 % provided that R&D expenses on regenerative subsystems are equal.