I don't have enough money to buy high frequency CRO can any on suggest alternative idea to build or buy CRO in low cost.

 

What is your budget, what frequency range do you want, and where are you located?

 

Your first oscilloscope will cost you nothing if you have a PC and an audio card with LINE input.

 

I don't have enough money to buy high frequency CRO can any on suggest alternative idea to build or buy CRO in low cost.

reach out to your local electronics groups or radio/television/repair shops and ask people of anybody has an old oscilloscope they no longer need or want- even 10MHz scope will get you to a better place than you are at.