Installing a toilet is one of the simplest DIY jobs there is. A plumber must charge what seems to most of us as an awful lot of money for a simple job, but we don't consider the total time involved, his overhead, and his profit. This is why many of us DIY as many plumbing jobs as we can. It is not that the plumber is ripping us off, but if we can do a job that would otherwise cost use $200 or more, even if it takes us twice as long, we have saved a fair amount of money. If you don't feel you can handle this, you might find a friend or neighbor that has some experience to help. Certainly, there is nothing wrong about hiring a plumber to do the work, and while labor prices will vary widely from place to place, $270 does not seem out of line.