Comcast pricing varies from market to market so the only way for you to know for sure is to call Comcast. Since this is primarily a user to user forum, nobody posting here on a regular basis can answer that for you.
That being said, just about everyone that has responded to this question in the past will tell you that X1 costs the same per month UNLESS you change something. If you add more boxes, add services or change your channel package the price will probably go up.
Most markets appear to have installation charges and you do not want to self install X1 unless you are fairly fluent with audio video gear...
How much does the X1 update cost?
You cannot do anything without Comcast either telling you, you are already paying to little, or trying to sell you an etymological sales pitch on a more costly bundle in the end! Never speak to their "customer service" as they are mostly either hired illegal or just cannot articulate the English Language, and are cheap labor, whom the Company does not really care anyways, as it is just a front and they all have a script to follow or hang up on you, or give you another fallaciousness of a number!! If you are going to insist on speaking with a person only speak to management! Not until customers can shut off their TV's, etc., and show some courage(Whch they cannot nor will ever.............look at our own state Rep.?) and self- control, and quits paying these absolutely fraudulent prices to the public(Believe me, they make enough to reap their large harvest, and still lower prices(Actually if they were smart..........REAL SMART......they would and could exploit a monopoly, and every other co. would have a heavy crimp put upon it, as K-Mart, Ground Round, Bonanza, Target, Sears,etc.,etc.), ANY SURVEY THEY ASK OF YOU IS ONLY TO GIVE THEM THE PYCHOLOGICAL EDGE THEY ACTUALLY CARE...............VERY CLEVER!! ANY WORK THAT WOULD CARRY OUT A PLAN THAT WOULD BE ANY DEVIATION FROM THEIR TIME or TECHNICAL HELP....................ANY SPECIALIZED KOWLEDGE IS NOT OFFERED WITH YOUR CONTRACT, WILL THERFORE COST YOU FROM A LITTLE TO QUITE AN ADDITIONAL AMOUNT! I WISH WE ALL STRONG ENOUGHT TO STOP THIS....................I KNOW I AM NOT ( ALONE ), BUI I THINK I COULD............FOR REAL!!!!!!!....................IF I KNEW THERE WERE THOUSANDS OF OTHERS OUT THEIR IT ACTUALLY HURT THEIR POCKETS AS MUCH AS IT DOES MIND! But I am on Social Security and 67 years old, so of course I am in a completely diffrerent class, which is OK! Don't anyone feel I am degrading or putting them down ..............I am not! Not in the Least! There was a time I wouldn't of given it a thought! Haha! So, please, no one take offence, as that would really hurt me! But what I say (Even from an ole man as myself)....................is still true!! JUST LIFE, I GUESS! GOD BLESS AND MERYY CHRISTMAS TO ALL!