maggie, try the bookpeople or redhouse - both will have great prices on sets of books or individual books
of course you can write what you like in the reading record - it's a guide to what's been read, not THE guide for the rest of a child's school days.
Dd1 is a fab reader, well beyond the types of books she brings home from school, most comments I put in are 'No problems, read easily' or "Excellent reading again' and even 'Not challenging at all' - not once has this been picked up on by the teacher, but I'm not concerned as she reads loads at home (own books and library books) The school is just another place she can get books from. Far better to have a love of reading of all sorts of books, not just those from a reading scheme in a classroom