Yes 50k coins is the requirement for running a masternode. Once you have the coins, you can rent a VPS ($5 per month or even cheaper) and input a simple command line given in the masternode installation guide by the devs.

Its better to have your own masternode than putting those coins in the shared MN program because there is 2% fee admin fee and you are better off running your own MN for $5.
All you need to do is pay the $5 VPS rent per month and the MN will be running constantly and in no relation to whether your Computer is on/off.