Federal workers don't get paid particularly well, actually. There's some competition among contractors especially if you have active clearance but nothing approaching SV.
Yes there's upward pressure on pay (and the cost of everything that pay buys) from the DC area but the DMV is no SilleyValley in terms of pay and costs.
Pay, definitely not (I live within extended commute distance and have gotten offers for senior dev at $80k and similarly insulting numbers) but it's pretty up there in terms of COL.
Wow, those companies definitely are low-balling (especially for a senior position in the DC area). Were those positions ones that required a security clearance, though?