So,
I got a new frame and it needs a BB30 crankset. I am searching around and have some questions.
1.) Why the heck are they so damn expensive!! (... not a serious question! just joking)

I have found some cranksets with non carbon cranks (specifically the FSA Gossamer) which I could buy and not have the wife get pissed!
So... can I swap the crank arms on the Gossamer BB30 with my SL-K series arms that are on Mega Exo BB.
Or.. am I going to be searching specifically for crank arms that go on a BB30?

Also... any advice on a fairly inexpensive set would be appreciated.

You can find SRAM Force sets at reasonable prices.

The right crankarm of the Gossamer is integrated in to the spider, so no, you can't use your arms.

What WhyFi said. Bang for buck, Sram Force is a solid BB30 crankset.

Another good value option are older Cannondale Hollowgrams - the silver, pre-SL versions. You can get them used for $200-$250 and they will be lighter and stiffer than anything else at that price point.

They are great cranks for sure.

There are also adapters that would let you step down from BB30 frame to GXP crankset.

You can find excellent used sram red for $200 often on the bay. New like $300 tops.

Force, good value also.