40-50k for a low mileage Hellcat is unrealistic. At that pricepoint, you're looking at a '15-'17 with 30k+ miles. In my opinion, the best ones to get are the '18 and ups. They have an updated UConnect and some quality of life changes that addressed some of the earlier configuration and dependability issues. On the plus side, the chances are fairly good that most of the bad blower equipped '15s and '16s have likely already failed if they were going to.
To echo what others have said, if you don't have a secure garage, don't buy a Hellcat. This isn't some sort of overreaction. Although I've never knowingly been targeted by a professional thief, I have been followed by some very over-eager drivers in the past. I don't know if they were trying to just get video of the car or if they were trying to see where I lived. Regardless, I did that whole drive past my house and started driving around the same block routine until they realized I was on to them and they pulled off after a couple of laps. Then I went home. Hellcats are a risky purchase in that they are actively targeted by thieves. Most car thefts are opportunistic in nature. Hellcats and similar high value cars are actively targeted. If a thief figures out that you park the car in an open lot (like at an apartment complex), it's only a matter of time before someone vandalizes it or tries to steal it.