Wondering if I should get these expensive tests done

Just searching for some advice...

I am a 23 year old very active female. I played lacrosse at the NCAA level and have never had any health problems. For the last two or so weeks I have felt some irregular heart beats and had associated shortness of breath. I went to a cardiologist, had a normal EKG, and he was not certain of what might be causing the problem. He suggested I get a 24 hr heart monitor and get a echocardiogram.
Only problem is when I asked how much they might cost (as I have not even scratched the surface of my insurance deductible) he said hundred of dollars (especially for the echocardiogram with doppler) which could be around $500 plus.

When I voiced my concerns about the cost he said I could wait and cut out all caffeine and see if it goes away and if it does not then do the tests.

I'm not really sure what to do. I'd like the peace of mind knowing exactly what is going on, but I don't want to be overcautious and broke.

Wow. You mean to say people have to pay for those tests in the U.S.? We get those from national insurance. I really don't know what to say I would not be worried though. How often do you have these spells of irregular heartbeat and shortness of breath?