The cream of the crop in this price range is the NAD 1020. Also look for the NAD 1155. You won't find a Linn for $100. The Apt/Holman is a truly excellent preamp but you would be lucky to get one for $100. More likely $150. They show up on ebay all the time. Avoid the solid state Dynaco PAT-4 and PAT-5 at all costs. Truly awful!
Cheap Old Preamps
I'm helping a friend look for a cheap (under 100$) old (tubed would be great but not necessary) preamp, and was wondering if you all had some ideas for what to look for (probably on eBay). I've been tracking some Dynacos, but the tube ones tend to exceed our budget. Are the SS daynaco preamps just sucky? His sources include an AR/XA TT and a really old Cambridge CDP. Amplification is a 40 wpc (I think) SS McIntosh amp (model unknown). Thanks.