Yeah, if you have any sort of stomach problems, it's best not to pile all your money into bitcoin and if you decide to buy it through Coinbase, it's probably best if you transfer it right out of there and into a safe wallet.  Someone here mentioned buying $2500 worth, but I'd probably buy $1000 at most.  But it also depends on what your time frame is and also what your outlook on bitcoin is.  Good luck.