Voyage (the Gravity Group) cost $8.5 million in 2006
A B&M Steelie (Intimidator @ Carowinds) cost $23 million (2011).
A B&M Flying Coaster (Tatsu @ SFMM) cost $21 million (2006)
A B&M Inverted Coaster (Patriot @ World of Fun) cost $14 million (2006)
A Gerstlauer Euro-Fighter (SpongeBob @ MoA) cost $2.9 million (2008)
A Gerstlauer Spinning Coaster (Tony Hawk @ SFoT) cost $6.5 million (2008)
A GCI Wooden Coaster (Terminator @ SFMM) cost $10 million (2009)
An Intamin Gigi Coaster (Intimidator @ KD) cost $25 million (2010)
An Intamin Agile Coaster (Fahrenheit @ Hershey) cost $12 million (2008)
An S&S 4th Dimensional Coaster (Eejanaika @ Fuji-Q) cost $31 million (2006)
I would make a guess but I am usually amazingly wrong on these.
How much is one of those Zamperla Motocoasters? One could easily be themed to reindeer, although the Xmas section of the park is pretty packed if you ask me...
An indoor dark ride/coaster like Fire in the Hole at Silver Dollar City would be a nice addition... and might fit the budget...?
The big draw at HW is the waterpark as Zack mentioned, so it would make sense for them to add more slides... *sigh*
Or, I'm thinking it could be a 2nd entrance to the park through the water park. It gives them greater expansion capabilities too. They still have quite a bit of land...
If they don't want the hassle and expense of a multiple launch coaster, a more adventurous mine train type ride might be nice.