I thought I read somewhere that it's Christine's money that Dylan is using to buy the booze.
As I see it, Christine's money is for booze, and
his money (or rather, what remains after the eventual date with Marie of the equally eventual money borrowed from Sophia's wallet) could be used to pay for the cab and "get help" to buy it.
In this regard, since I assume that Dylan will use the same cab that took him to the gas station/liquor store and then have it take him to Christine's house, he could bargain with the taxi driver for a lump sum that would include, in addition to the cab ride, extra money to get him to help buy the booze.
Anyway, I will ask L&P whether in this update (as in v.0.180 and in the date with Marie) money will be a limiting factor in Dylan's success in accomplishing his task, and I will keep you updated on his response, if any.