Most laptops use a 2.5inch IDE drive.
They are quite expensive compared to a 3.5inch PC drive.
If you want a second hand drive there are usually plenty of them for sale on Ebay.
I have bought two in the past from Ebay (for about £10 each) and use them for portable storage.
The 2.5inch wide is pretty much standard but you need to check on the thickness of the drive.
I think most are 9mm but some are 12mm and there may be others.