Funny how attitudes change. Not so long ago, people who posted on this site that they had or were about to pay for a TR were abused no end. It was seen as an unacceptable decline in FO T&C's. It seems that perhaps this view was correct as this thread would indicate that a TR is almost essential to securing that first job.
I cannot think of a situation that would lead to me paying for a TR. I work to live not live to work and paying tens of thousands of pounds just for the privilage of being competitive in applying for a job sticks in the throat a wee bit. As much as I like to fly and would like to continue to do so, I will not pay for a job (apart from the not unsubstantial cost of getting my license in the first place that is!)