It doesnt always pay to buy things on the cheap! they might look a good deal now, but they'd probably blow up and then youd pay more for another set! although on the other hand they could be fine and a bargain but better safe than sry ey!
For an extra £20 you can get some inifity's, thats what i have, quite popular decent quality and very affordable speakers!
jsut some general advise: before you buy anything that looks cheap on ebay,do some research and look around the shops,esp online. u may find that the new price is similar to that on ebay! u can get infinity 6x9 for 50 quid in halfords if that offer is still on? aint sure tho,coz they might hav cleared out all their old stuff by now!
oh if u want cheap but good quality 6x9's,get the jbl ones. i got em and they dont sound bad,and for 35-40 pounds (brand new),u cant go wrong! 100w RMS.