Slow cookers - where can I get a good, reasonably priced 'oval' one?

[Gateau]

Hi,
I have just bought a slow cooker recipe book and am about to invest in the equiment. The book states that the oval-shaped cookers are the most versatile. I want to spend as little as possible as I'm starting mat leave next week, but obviously want it to serve its purpose!
I was thinking of getting an Asda one but I think they're round, not oval.Can anyone please recommend a 3.5 litres one that doesn't cost the earth?

I got mine in Robert Dyas, not sure how big it is but they had several to choose from, all oval. It was £20

I got one from Waitrose/John Lewis for about £19. I'm not sure how many litres it holds.

Thank you.

I bought one in Sainsbury today. It's 4.2 litres, oval and cost just under £20.00