I have been waiting for someone else to jump in with an answer, but since no one has ...
With the possible exception of the Yeasu ($4000) solid state amp, I don't think you will find a single amp to cover 160-6. An amp with that wide coverage is not as easy to design and produce as the typical transceiver. You are much better off with two separate amps. 6m amps are not as common as HF amps, by the way.
As for sticker shock, welcome to the real world.
With amps, you tend to get what you pay for - bottom end amps have cheaper components and construction and fewer bells and whistles. More expensive amps are better built, longer lasting (if not abused) and so forth.
I suggest to consider buying a used amp from someone you are familiar with. The AL-811 and Al-80A and B are often available for under $500 and $750, respectively. Both use inexpensive tubes and are easy to use. The Heath SB-200 is another good, used amp that is often moderately priced.
Go through the amp reviews and do some reasearch before you make a decision.
I hope this helps.