"Dozens" of non-Vault firms in a state that pay upwards $2k/wk for a summer position? Interesting. I'm only familiar with the NYC and Chi markets, and to a lesser extent the DC and LA markets. What markets have dozens of non-Vault firms paying first years $104k/year?
As I qualified in my initial response, my figures assumed the poster was "asking about the conventional definition of 'summer associate,' i.e., a law student working between 2L and 3L (or 1L summer if exceptional) at a major, multi-office law firm, or at least at a firm with a large office."
Galt gave a good working definition of how summer associates are paid: "Summers get paid the same salary as first year associates pro-rated for 10 or 12 weeks." But even that definition assumes that we are talking about a "summer associate" properly so called.
Many non-Vault firms that employ people for their pre-3L summer call such students "summer clerks," and many (if not most), regardless of their job title do not pay those individuals the same as new associates (and certainly don't wine and dine them all summer). At many such firms, after graduation, they return to work at the firm (often during bar prep) - at their pre-3L summer pay rate - until they receive passing results and are sworn into the bar, at which point their pay goes up (albeit, in most cases, nominally) to their "first year associate" rate.