I am using Creative 2.1 on my pc and Microlab 2.1 on my TV...I also have seen Altek 5.1 performing. I bought the Creative one for 2500 Rs. about 2.5 years back. Trust me, it was really worth the money. Great quality for extremely low price. It has not gone down in quality. The best thing is you get a wired remote control so you can keep it next to your keyboard. I have heard that such quality Creative ones are now quite rare. But if you're buying an old one, probably that quality should be there. But 4500 for 1.5 years used is too much.
Microlab one was more expensive but equally good. Bad thing is no wired remote controller. So, to change volume, you will have to reach the sub-woofer. That's why I have attached with the TV.
They say Altek is good, but compared to Creative and Microlab, I think it's not good. Creative and Microlab has better bass enhancement. I have also bought Intex sub for my sister. It was truly a piece of shit.
So, go and ask for prices of 5.1 subs from the market. It will be lower in coming months cos of tax reductions. Better you buy new ones. Make sure you also check the wired remote control facility cos if you have to bend down and reach the sub woofer to change volume, it's gonna be a pain in the ass. Trust me on that.