My TM was 2k. I would say it took 4 months before the EXTRA money it earnt paid for itself and that was with a few teething troubles in the first month or two. Now it gives me far more earning potential than my Speedster and with very little effort.
Buying second hand is a good way to go, but not for the faint hearted.
What I can't understand is people are quite happy to get a sparkling new van on tick but the idea of doing it with as Simon would put it 'a money making machine' LOL or an entry level TM, suddenly is too much of a risk.