Cheapest book shelves

Short of bricks and planks, what are the cheapest bookshelves that money can buy? Our attic is strewn with boxes of books making most of them unreachable so we've decided to put in some shelves. I found these nice plastic ones at £35+VAT for a 5 shelf unit. A unit is H:120cm W:80cm D:40cm which means we can shelve paperbacks two deep with 30cm clearance enough for most books. They don't have backs or ends so we might need some cheap laminate but books seem quite happy to stay on shelves usually.

I reckon we'll need at least four, to start with and that's £180 straight off.




Does anyone know of any cheaper alternatives? They don't have to look nice.