Traditional plastic (or PVC) nappy covers/pants are, quite frankly, disgusting and should be outlawed! You would not wear them yourself, so why make your baby wear them? Most importantly, plastic pants are hot and sweaty, and they tend to leave painful red marks on the waist and legs. Because of this environment, sweat rashes easily develop, especially with night nappies. They may seem very cheap, but because they go hard so easily and need to be replaced, it is a very misleading economy. Bear in mind that the German research warning of the effect on sperm of the overheated atmosphere of a disposable applies just as much to an overheated cotton nappy - which will be the case if plastic or PVC wraps are used.
You will need at least three wraps at each size, to allow for one on, one in the wash and another for accidents. We recommend you have a ratio of 1 wrap for every 4 nappies that fit at each stage to ensure you don't run out. The younger the baby the more you are likely to need in 24hours.
I would recommend using the same cover pant for no more than 12 hours or so at a time. So, assuming you wash every day, your baby will wear one wrap overnight, another the next day. This assumes that you choose a wrap with a laminant interior, which you can simply wipe down each nappy change if you wish.
As a general rule cover pants should not be sanitised or tumble dried, as this may damage the waterproofing. Some can be tumble dried on low, but it is rarely worth the risk, as they usually dry very quickly.
When you put the cover pants on, feel around the top and the legs to make sure it completely covers the nappy, otherwise the wet will wick out onto clothes. If you are good with a pair of knitting needles it is worth doing a quick web search to see if you can track down a pattern to knit your own wool pants.
You also get a choice of nappy wraps that fit birth to potty or sized options. Sized options are more expensive as you need to replace them as baby grows. The fit however is MUCH better at each stage which in turn makes them far more reliable. You are also spreading the wear across your nappy system so if you have more children the wraps will be in better condition.
Our best selling wraps for over 15 years are the Motherease covers. Motherease covers are truly wick resistant. Wicking is where the outer wrap picks up moisture from the nappy underneath (like if you put the corner of a tea towel in a mug of water the water would slowly travel through the tea towel). Many other wraps claim to be wick resistant and some are very good but NEVER as good as Motherease. We're not being paid to say how good Motherease wraps are, we just wholehearted believe they are fabulous! If anyone ever comes to us with a leaking nappy and we know they are using a Motherease wrap (in the correct size) we can guarantee we need to look at the nappy as the issue and not the wrap. My own Motherease wraps bought for my first child lasted him, his two siblings, lent to friends, hire kits and now lurking in our demo kit. People never believe it when I tell them they are over 12 years old.
If you are on a budget don't compromise on the quality of your wrap but compromise on the nappy underneath. An excellent wrap will make even the cheapest nappy work.