If you're looking for sand protection you only really have a few contenders from the big names to choose from if you're after a full blown case. Lifeproof, Otterbox, Griffin, and Incipio - all £50-60+ though.
I had a lifeproof and it was ok for what it did, but had loads of problems with the sound and the screen looking a bit rubbish. They now have the new model where it seals on the edge of the screen so doesnt effect the look, but wouldnt really offer the protection from sand scratching your screen you need.
Incipio Atlas peeked my interests because its screen protector is glass and is reported to not rainbow the screen but a few people complaining about the screen being less responsive. A common trade off for all the waterproof/dustproof cases though.
If you're after cheap and you only want it for protection on the beach your choices are going to be limited to the bag style protectors, not idea if you're wanting to record.
All the waterproof cases are at quite a premium.