Re the PS, personally, I think it is not such a good thing to base too much on it (and I think that mine was fab; although a tutor might think differently, but I hope not
). If you go through the Oxbridge interview threads, you might be amazed at the no of ppl saying 'now I need to go and read the books that I said I read', 'I wish I had not said I'd read 6 books - I shall never be able to read them all before my interview' etc. etc. A PS can be bought, and it can be faked. IMHO, for unis to place too much on them, is not wise. Grades on the other hand are 100% authentic. Usually, the person they are ascribed to is the person who took the exam to which they relate (ignoring coursework of course).
Re the affordability of the course, surely, only time can tell. Being able to pay for the course (loans etc.), doesn't necessarily translate into the student being able to afford it