I have a feeling Modelsdirect are not necessarily one of the well regarded agency. My dd is a model and she is 3, her agency did not ask for any money (they take a comission on each job), however there is the optional opportunity to go into their 'book'. This is once a year and you pay for the shoot (about £60) and pay to be in the book (about £75). You do get a bit more work by being in the book, but I don't take my dd to castings, so I figured the only way she would get jobs is by being in the book.
So far she has done Tesco's, Aldi, Toy's R Us, Startrite, and various other little things. Her best job was Tesco since she is currnetly on teh cover of their Christmas magazine!!!! (Quick boasting mum! )
She gets about £50ph, minimum of 2 hrs work, with 20% agency taken off this. 95% of the work is London based, and since we don't live there, we have to account for travel as well. So she doesn't really make much money.
Overall less expenses she has probably made about £500 last year. However I pay expenses and put all her earnings into her bank account.
Seriously, don't do it especially for fun, as there is no agency (bar dodgy ones) that will take you on if this is the case. Remeber all the reputable agency's get about 20 letters per DAY from parents sending in photos of their kids. I was the only person taken on in a month with my agency and this was because I had insider information (I used to work for a magazine that used models from this agency!).
Good Luck, but think really really seriously about this. Even the day taking photos is no fun, you sit around for hours, they can't play because teh equipment is all over the place, sometimes they 'forget' to offer a drink even! My advice is don't bother, as I said I only do actual jobs and not castings, which even for little kids are a case of 'next, next, next......'