Misread the question (just got back from a long trip) but understand now.
In that specific case I would add it to a specific tournament winnings but not to a bankroll. You could add the value of the tournament buyins as bankroll but the rest, since I assume it can only be used for the trip, can’t be part of the bankroll.
In general, if a prize is in addition to (like the platinum passes they did for that MoneyMaker tour) I would not count that as a prize but if a prize is in place of (like it seems your trip is) I would say that prize is the winnings and the approx. cash value can be put in.