Literally any speaker you can buy would be better than this, just make sure you buy the right size and get a mounting adapter for your car. If you have a little bit of money to spend then make sure you look at RMS W and not total / max W (watts). Also for front speakers you would want components, and 1 or 2 way in the rear.
Quite common for cheaper speakers to be over hyped with a high max w or 3 or 4 way output speakers (max W doesn't translate to good quality sound) and 3+ way speakers have less punch and more sharp piercing / tinny noise, basically too much going on.
Long story short, if you just want a cheap replacement and don't plan to spend much on the sound system then a trip to supercheap for some basic speakers will be fine, just don't get sold on the massive spec sheet from sony with their 400w 3 way speakers :p
p.s, the cheapest place for car audio is Trademe, there are a few small audio shops who sell there with low margins compared to larger companies.