Allergy’s and air purification devices-?

I was thinking of buying a JML fresh air globe, but after looking on previously asked questions they don't seem to be all that good.

I was wondering if anybody could recommend a device (like the JML globe) that removes dust and other allergy triggers out the air.

I don't want to spend a fortune, up to about £50 would be nice.

any ideas?

PS: Sorry for the boring question, - but I promise 10 points to the best answer... yes a whole 10 points!!! wow what a deal! *Ahem*...