I have a friend who, like you, has her RN and wanted more money. She completed an online program for Echo. Now, she is very happy as a traveling Echocardiographer. Currently, she is in northern California making $42/hour + car allowance + housing. SWEET! I do know that in different regions the pay can be as low as $20/hr, starting, to $35/hour, starting. So, to me, the opportunity is there especially if you have the abililty to travel.
This is just an option you may want to explore.
I hope this helps...even a little!! Good luck.