good timing, our currency is down the toilet atm.

the prices below are calculated for 1 USD = 200 HUF [atm its 1 USD = 225 HUF. one year before it was 1:140]
fresh tapped quality beer 0.5L : $2.5-3.5
vodka, whishy, tequila, jagermeister 0,05L : $3-$5
quality weed 1g : $10-12.5
I haven't found any program guides in english, but will find you one later.
About night clubs/sex clubs : I don't know of any and will ask someone for you, but the default is to
avoid all the places w/o good reference. Do not just sit in a taxi, but always call for one, some companies who won't screw you over:
City Taxi
Fo Taxi
Entertainment:
A38 Boat : Best events ever, but for some you have to book tickets in time. Check the calendar ;)
Corvin Teto : popular place in the middle of the city [only in hungarian, but check the events in March]
Szoda
Szimpla
Fetish/BDSM shooters: contact 21 Sextury Cash.
Hotels: will look this up for you, but need more details about what kind of place you're looking for / what price range you're looking for, etc.
However I live in another city ~90 kms from Budapest I am more than happy to give you any help you might need. Check my whois info for my phone number, and save it: in case you need help or whatever.
Where not to go: to be honest, I've heard LOTS of horror stories about foreigners getting ripped off badly in nightclubs, etc.
Never get into a random taxi and ask the driver to "take us to the best nightclub!" this is not working here!

You must have a list+map from places you want to visit, and you can have a GREAT time in Hungary. But if you come w/o proper plans and information you can have a very nasty experience as well. Young people are usually good, nothing to be afraid of. Use your common sense: leave the place if you don't like the people inside or if you see some suspicious bad looking guys. Also do not enter places where the staff who is at the entrance is not happy and helpful but bad looking or whatever...
What not to do: you're not allowed to smoke weed and have any kind of drugs with you. They won't check you at clubs, and policemen won;t check you either, but just don't roll and smoke a huge splif in the middle of the city.

) However if at places you see ppl smokin' feel free to do it as well. Also you can ask the bartenders or friendly looking ppl for this. Do not walk on the street with open bottle of alcoholic drinks. Its not allowed.
Lot of nice places to visit, but I need to know how much time you want to spend on this or are you interested in this at all.
Feel free to ask any questions, I am happy to help you making the hotel reservation on request and help in similar things.
Peace