yo Drizzt - Salvatore fan?: )
check out the a38 boat they have an afternoon thing from 4pm - 10pm. open air chilling + drinks on a boat while locals play - sound is pretty cool and theres usually something on the boat from 10pm - can range from techno to alternative but they will have flyers hanging around.
http://www.facebook.com/fridayata38
If you're looking for gigs on the dnb tip check the Bladerunnaz facebook -
http://www.facebook.com/bladerunnaz
Every wednesday theres a night called "Rewind" which is like a mixed night, early on it's more chilled stuff then after midnight it's proper rinseout mixed genre crazyness but it's pretty much in the centre / cheap / and you can chill @ the roof of a building in case the music is not your thing. It's at the already mentioned 'Corvin Teto'
another popular place is Szimpla, it's one of those condemned bulding bar thingies which Budapest has loads of but this ones the most popular -
http://www.szimpla.hu/budapest/home?Itemid=22
Akvarium - middle of the centre aswell, half open air / half club (but the club part sucks so I'd just stay outside) usually loads of people prices are decent
Cabs :
Max Taxi -
http://maxtaxi.hu/
Taxi Plus -
http://www.taxiplus.hu/
these are the cheapest and they usually have english speaking operators
I'd advice against getting random cabs on the street cause they usually go berzerk when they clock you're a tourist.. it's annoying.
Basically where ever you wan't to go, if you don't go too far from the centre you should never pay more than 3000 (thats less than 10 pounds) and even that's usually with a nice tip so watch that.
if you have any more questions drop 'em in here and i'll get back to you - nice1!