The commission of sustainable development though stressed upon use of RE systems replacing fossil fuels - it's use is marginal till date. Pressure over land use and economy limits the use of solar or bio-fuels. Wind Energy resource gets limited being site and time specific. Ocean Energy systems (OE) though have abundant resources and require no land use, but its initial huge capital investment to ensure survivability, limits its large scale use. The present study has hence been taken up to examine the scope of cost reduction inclusive of the three OE systems, such as, Wave, OTEC and Tidal schemes. It included sensitivity analysis for replacement of cheaper construction materials as well as design innovations, for wave and OTEC schemes. However, for Tidal schemes it was on the development of threshold limiting value of barrage constant that served as an instrument in making cost-optimized barrage planning. All these approaches as developed could be shown from case studies made of Pelamis and Wave Dragon type wave energy converters, 100 MW OTEC unit, as well as from a functioning and also a few proposed barrage schemes as planned. RandD areas were also identified on cost reduction aspect for both wave and OTEC schemes that holds wide promise on economy as well as survivability, including considerations of futuristic wave density increases in the eventuality of global warming. .