Actually no, at least on Jackson custom sheet limba as korina costs as much as mahogany, 60$ extra compared alder etc. I think that the cost of limba is mostly just Ed Roman hype.
If you're not afraid of going through european routes, I've seen a lot of good press (but have never tried them myself) about Ran guitars in Poland and Shamray guitars in Russia. Also Feline guitars in UK had guitars which seemed to be really over the top in excellence. Those polish and russian guitars can still be cheaper for you in the US, as the cost of work and some materials too is far less than in the US, without any lack of luthiery skills and experience.
I'd also be interested in other european manufacturers, can anyone help?
couple more things
1) limba isn't all that more expensive than mahogany - and its pretty nice sounding and very very cool looking (i've got a nice pic in my under construction/inprogrss page
Fatty's next guitar from me is black limba
other buildings
JohnJohn
Zerb
Thorn
Driskill
McInturff
McNaught
and then Anderson and the other strat/tele style builders