Sam's sex drive isn't nearly as strong as Dean's. Yet he's far from being a saint in that department. It's just that over the years he's learned not to become attached.
He has only one photo left of Jessica-a candid of her sitting at her dressing table brushing her hair wearing a filmy blue nightgown.
Jess, Madison, his own mother for god's sake. Women who love him end up dead. So, sure, Sam probably could still have any woman he wanted.
$200 is a small price to pay an anonymous escort who will walk away alive in the morning.