Hey check this out.. could this be what you're looking for??
These files represent the boundaries of the post-2010 census state
legislative and 113th Congressional district plans as collected by the
U.S. Census Bureau in Phase 4 of the Redistricting Data Program (RDP).
These shapefiles are the official boundaries as represented by the
state liaisons, including split 2010 census tabulation blocks.
It just occurred to me that you may be more interested in the officials who won the elections, which will be different from year to year, rather than the district boundaries, which change infrequently. If that is the case, the Tiger/Line data will be of little help, in as far as I can tell it does not reveal the party or the official holding office.
In the 2012 Tiger/Line data, you can get shapefiles for ZIP code tabulation areas (492 MB), as well as the 112th congressional districts (44.6 MB). Of course these are free.
I realize that you're wanting data for the 113th congress, but is it really so different from the 112th? (Please forgive my stupidity, I really don't know.)
Depending on when your project is due, could you possibly create the application now, against the 112th dataset, then slide updated data for the 113th congress into place once it's released for free through Tiger/Line?
...as far as the differences between the 112th boundaries and the 113th, I'm skeptical that they are so different. Here are two graphics comparing the 112th with the former, the 111th (showing the St. Louis area---go Blues---and the Boston area---go Bruins), and I cannot distintuish any differences between these boundaries. If there is a significant difference, you should notice a blue border (112th) below the red one (111th)..
StL: [image removed, irrelevant now]
and beantown (Boston): [image removed, irrelevant now]
However... again... maybe there is something I don't know to be extra-scrutinous of? My gut-level instinct is that these boundaries may have been redrawn following the 2010 census, but I doubt they are frequently redrawn. (Afterall, the whole point of the census is to establish population counts then set these representative areas.)
Here's Texas, somewhat in response to comments, however admittedly this is 111th vs 112th. Just adding it to be consistent:
[image removed, irrelevant now]