$100? Used would almost certainly get you the best bang for the buck. Brands that I would consider used would be:

-Creek Passive preamp (The most neutral of the possibilities but you'd give up some bass and Dynamics and your source would have to put out enough gain to be able to drive the input stage of the amplification. Making sure that the cables were all as short as possible would be a big help.)
-Adcom (I had a GTP-450 for a while and it was nice,but other would be good too)
-Parasound (I had a P/HP850 and it was good, but other models would we worth considering)
-NAD
-Rotel

A hundred bucks for a preamp/volume controller with remote is a tough one.

Start here.

That is an old link, but perhaps you can trace the person and see what's new.

I know nothing about his actual product, but the price and parts are intruiging.

Perhaps this?

Google "volume pot," "remote," and "attenuator" in different combinations and then if you find something cool, post it here and we can try to help.

You could look for a used Parasound Zpre Stereo Preamplifier.