CARDS:  as with headphones, this is another item that is often overlooked when it comes to budget.

again, there's a large range - costing a few £'s to the higher spec ones that can cost, depending on size, up to £100.

I could write a long post on all the different brands but its much simpler to say that there's one brand who always, always come out tops for stability and reliability + as long as you buy their fastest, highest class rating ones you won't have any read / write issues:

Sandisc - the prime choice for most folks as they are the most reliable. I've used them for years without any problems for example.

other makes that get good ratings & are quite widely used include:

Kingston
Lexar
Hama (not used those myself though & they do appear to be on the cheap side)

for audio you need cards with fast read / write speeds - don't get ones that are below class II (though this rating system is now increasingly not used) - the card needs to be 24x write speed rated at least, especially for multi-channel or high rate recordings.