What time of year? There are a lot of State Parks that could fit the bill and the venue/day use fees are very affordable. (I think the big, purpose-built venues at Kingsland Bay are the exception.)

We had ours at Mt. Philo, and our cost for the venue ended up being under $500 for the Lodge rental and day-use fees for our guests. Ranger Pam was awesome to work with and you can't ask for a better spot for photos. Depending on if you want a "mountain" or "lake" wedding there are a few options that could work, as far as the distance and facilities.