In one day you can go up to Drei Annen Hohne, up the Broken, back to DAH and then go south to Eisfelder Talmauhle and back to Wernigerode.
To fit that lot in you need to be on the first or second Steam train out of Wernigerode in the morning. All by steam. last year that would have been 35 euro. Loads of options but watch out for a day full of railcars if going over to the Selketalbahn (Quedlinburg) - mostly steam is possible but check the timetables carefully.
Timetables - http://www.hsb-wr.de/mehr-erfahren/fahrplaene/