Why not go for BOTH Senate and House? No need to concede either to the Dems. And if interest in conservatives is generated by a Senate primary, then that would likely carry over to the conservative House candidate in the same election.
There are other tea party groups out there, maybe some of them can get out there working to get more conservative house members.
The TPX operates on a limited budget dependent only on contributions from interested parties.
Individuals of course can do a lot to get Conservative Tea Party type candidates elected, so consider doing some of it yourselves if you aren't already.