I'm no expert on Berlin. My experiences in Berlin are limited to only one trip and I was with a gaggle of co-workers almost constantly so I didn't have the opportunity to pursue the hobby.
But I did keep my eyes open for whatever scene I could spot in the papers and phone book and on the streets while I went around various parts of West & East Berlin over 6 days. The only thing I saw was SW's on Orienenburgerstrasse in the East. I now know that there are other options but I'd suggest figuring out what they are before you arrive in Berlin because, to a non-German speaker, they were pretty much invisible to me.
I'm assuming what I saw on Orienenburgerstrasse were girls, not crossdressers, but I don't know. They were standing in the street, which is very busy with traffic and lined with nice places to eat and drink BTW. The girls were making no bones about what they were doing. You can't miss them but perhaps you need a car to get them to go with you? The ones I remember most clearly looked pretty good at a distance - nice bodies, very extravagent outfits with thigh high boots.
Hopefully someone with more knowledge of Berlin will chime in. But I'd recommend alloting more money to Amsterdam where you've got a great selection of sure things, as attymn says. There are so many choices in A'dam you might well find that time and energy will be as much of a limiting factor as money. Then for Berlin do some research about what you're looking for before you arrive, have a go, and let us know what you find.
You might find this site to be useful in your research:
http://www.berlin-diskret.de/berlindiskret/
Have fun!