To be honest I was one of those "went on subs then switched to crack" people and if not for my relapse and it going completely on the back burner for months I am not sure how easy stopping would have been. At the point of my relapse I had been smoking crack on and off but always on my payday for about 1.5 years. I would never go over board and always had money for other things so it didnt seem like a huge issue. Its funny how easily it corrupts your thinking like now that I am on methadone and approximately 6 months since I completely stopped smoking and now 25-30 dollars on a single days expenses is a lot back when I was smoking I would think 20 dollars a day was nothing. Come to find out now that I am fully clean off dope and crack for the first time in a long time 20 dollars a day is a shit ton of money.
My point is it is a very strange drug and you will find yourself making excuses for it, "oh its 20 dollars if I get it with a friend we can get double for ourselves, etc" before you know it you have at least one day that is you "fun day" and youll take it whenever you can. And because there is no physical withdrawal it is even easier to view it as not a problem. I would definitely stop before it becomes something you just do and think it isnt expensive.