Huge Cost, Broken Heart

So, the quotation to repair my iMac came. The failure shows it is mother board failure, and without warranty, the repair cost stands as high as 21800NTD, which is around 700USD. 700 USD is good to get a fairly good PC system, and the new iMac costs twice as much, with warranty, most updated hardware and software. If I shell out 700USD, then the system still does not have warranty, and who knows when it is going to fail again. But I know I'll be very unhappy to have to use PC again. Not an easy decision to make.