HAve been inside several PCP's...certainly not all of them, but a few and have looked at the take-down of many of them. KNOW i can take apart a Discovery completely without any specail tools or training...can replace the few seals ther it has...can take the trigger all the way down (it's super simple). given a handfull of spare parts, could keep one running for decades.
IN your situation, needing to be self reliant, the Discovery is probably as easy as PCP to keep running as any on the market.
If i were dead seripous bout keeping one working for a long time, would buy the Discovery, avoid the discovery pump, and buy a Hill pump. Hill pump isn't magic, but it is the easiest to rebuild of any on the market today. The rifle, Hill pump, spare seals for the rifle, rebuild kit for the Hill, rings, a resonable scope sight...call it $630-$660. Use the spare $ to your $700 limit to buy as many good pellets as you can.