I've worked in two brewpubs -- one as the brewmaster and bar manager, that lasted 4 years; the other as front manager that barely made it a year. I can't speak to the start-up numbers for either venture. However, the first one spent about $250k to start up, and that was already an operational restaurant when they converted.
The brewpub business, when it is going well, is a hell of a lot of fun. It's busy, stressful, hard work, but the rewards are great.
However, you need to understand that a brewpub is really TWO businesses: a brewery and a restaurant. Neither industry has a high success rate for start ups, and both are pretty labor intensive for the owners.
I'll give you a key, however: advertising. Both of the brewpubs I was with ran afoul of the advertising industry by not getting bills paid, so they couldn't continue to advertise. So it became harder and harder to attract new customers.
Secondly: the food and service are absolutely critical. The beer will bring people in, but the food will bring them back. If you let the food slide even a little, you will get a bad reputation in the community. Remember, if 1 customer has a bad experience, he will tell 10 people. There's 10 folks who won't come. If 1 customer has a good experience, she will tell 10 people. There's 10 folks who may or may not come in.
I don't mean to be a downer -- I loved working in that industry -- but go in with your eyes wide open.