However, for clarification, a +1 sword is 2,000 gp (well, 2,310 with the cost of the sword itself, but whatever). A +2 sword is 8,000, and +3 is 18,000.
A +1 paralyzing sword is the equivalent of a +3 sword, and so costs 18,000. It has the paralyzing ability, but only a +1 enhancement bonus to attacks and damage. Clear?