R.O.
You don't have to take the bottle away, plenty of kids have had bottles until age 2 or later. When you are ready to take it away, I suggest you go cold turkey. It's the going back and forth that makes it hard for your son. Just gather up all the bottles put them away, and use only the sippy cups. Your son might be frustrated at first, but trust me, he will be fine. Stay committed to your decision and be consistent. Because if you go back and forth, telling him no bottle, but a day later he gets a bottle, he'll be confused and frustrated. You decide when you are ready, and then make a decision and stick to it. Don't apologize to him, just be matter of fact about it. If he asks for a bottle consistently tell him, "no more bottles, we use cups now." Depending on the temperament of your son, it might be easier to take it away now than when he's older. My son went cold turkey from bottles to sippy cups around 14 months. I was pleasantly surpised with how well he adjusted--his day care started using sippys and the same day I took his bottles away. You never know, your son might surprise you too!
ps. Nuby makes a sippy cup with a clear "nipple" like spout, try that, it might help the transition.