There is the gaius gracchus society for classics/ancient history. I think there's also a general history one but I can't be sure. Gaius gracchus has toga/themed parties, Greek/Latin reading groups, movie screenings (and tv shows) - what's on really depends on the committee for that year and how many members are actually involved (ie turn up to things after Oweek).
A lot of societies hold various bbqs, pub nights etc. depends on the society as to what they do/spend their money on.
I don't think they've released access card pricings for this year, however last year it was between $90-100 if I remember correctly. They had a lower price for returning members (around $90), and you can also purchase life of degree membership (3 or 5 years) which offer a saving pver buying a new one each year.
I don't know if it's continuing this year, but for the past two years the unions and the colleges teamed up so that college kids all got access cards (free/incorporated into fees). I did hear a rumour it wasnt happening this year though.