Generally, €50 is for S&F (suck and fuck) for about 15 to 20 minutes. If you want longer, then they expect you to pay another €50. In the booths, the pricing roughly equates to €150 for one hour (approx $200ish). Outside the booths, escorting starts around €160 per hour (
example) and goes up from there.
For pricing and negotiation technique in the RLD, see this FAQ:
http://www.ignatzmice.com/RLD_FAQ.
For a portal to most everything about Amsterdam and the RLD:
http://www.ignatzmice.com/