I used Erskine Group - was very happy with the result and finished it for far less than $100k. My biggest expense other than seats, were carpet ($5.8k), buying a surround sound processor and projector ($6.5k). Seats were $16k. I figure I spent around $40k all up on materials.
That said - I did everything DIY, except for laying the carpet. I figure between Dad and myself, we put in about 200 man days of work. Here in Australia, the day rate for a general contractor is around $300 per day, so I figure I saved myself somewhere around $60k in labor costs.