That depends. What make are they? Could be hottuning/raceland coilovers for that price, i've had a set on my civic, and they were great
 
I had the raceland eBay specials on my a3, a lot of the golf guys on vortex swear by them but my ride was hard as nails, very bouncy and I'm sure it's destroyed my spine somehow

I would advise against them buy if you just want it slammed and have niceish roads then why not go for these
 
be prepaered for a rock hard and bouncy ride. with suspension kits you get what you pay for
 
why not go for AP coilovers or wietec, yes there a few more quid but least they have good reviews and you still paying under £400 :shrug: i have AP coilovers and i really like them
 
i got racelands on mine. they are cheap but look and feel great tbh. its not uncomfy and my car has poly bushes all round pretty much at the arches front and back.

avoid ta technix tho the droplink mounts bend so ive read on here
 
there good coilovers, iv dealt with them twice, once on a polo GT once and now on my ibiza FR, for 170 u cant go rong, i think mine came from belgium.
 
iv just bought a set of the hottuning ones for my ibiza, i had them fitted to my old golf mk4, their still on that car and working perfectly, i didnt even think the ride was too bad. As said you cant go too wrong for the money.