It depends.
The lesser-used CAC charges an "initial fee" of 800 euro, but tacks on 300 euro if there is a response. Then, it will charge another 800 euro if the Respondent increases to a three member panel.
The NAF charges $1300.
WIPO charges $1500, and will charge an additional $500 if the Respondent requests a three-member panel.
Very few complainants do these in-house, so the UDRP fee is only a minor component of cost, since a lawyer will charge them anywhere from $2000 to $10,000 to file a UDRP, depending on the client and what the lawyer can get away with.
However, this notion of "I'll price it below a UDRP to make it a rational choice for them" doesn't actually work over a large number of trials.
There are organizations who will not pay $1 for a domain name if they can win a UDRP, because they believe that it only encourages more such names to be registered. So, even if you are asking them for $500, they will happily pay $4000 to take it from you in a UDRP. Their reasoning is that if they give you the $500, then you'll simply go register more variations of their mark(s).
Likewise, there are organizations with marginal trademark claims, and they want to establish a record of winning UDRP cases for other reasons. For example, they might be seeking registration of their mark, and have run into issues with proving whether their mark is distinctive. In that sort of situation, they don't care what you are charging for the name, they want a UDRP decision. There are a couple of other scenarios like this, where the decision itself has an additional value to them beyond just getting a domain name.
Additionally, there are some which simply file ACPA lawsuits, and if you are in the US, then you are going to have issues (although for the time being, the courts have slowed tremendously).