Don't members of Congress get to use official funds (i.e., not their own money) to travel back and forth to their home districts? As I recall, besides travel funds, they get quite a few other additional perks to cover their expenses beyond their salary (franking, congressional gym, cafeteria, campaign contributions, lobbying "gifts", insider trading benefits). And yeah, lifetime pension and healthcare after 5 years of service. So yeah, not much sympathy for "getting by" on $174k, even if it means having to rent a place in DC in addition to maintaining a home in your district. They could rent a really nice apartment right on Capitol Hill for $2000/month for the entire year (even though Congress is in session only about 10 months), and still be left with $150k annually. They should be able to scrape by on that $150k back home.
And of course, once the gig is up, they will make a huge amount of money as lobbyists, seats on corporate boards, talk show hosts, and so on. Almost every member of Congress is independently wealthy (to the tune of millions), many with tens or even hundreds of millions of dollars net worth. There are only a handful that are not already rich, and that's because they're young upstarts who had an unorthodox move to Congress (such as tea partiers that came out of nowhere to win their seat). They'll be rich soon enough once their Congressional gig is up.