I'm not sure what other peoples views are on this, but I would definately advise against paying for you own TR. The reasons why I think this are two fold;
Frstly, from what I've picked up, employers don't look favourably on potiential first-officers that have payed for their own TR and don't posses any line experience.
Secondly, TR's are massively expensive and say you complete a TR on a 737 (seems to be the most popular at the mo) then you've totally norrowed your target market. Who knows where the industry might be in 5 years time?? will the low cost airline industry continue to expand at such a rate? or begin to die out as scheduled operators compete for passengers.