Ask a friend to buy an amp and do the install for you and if he charge nothing for the service, then it will maybe cost you 50$ approx. Many people have electronics and sell them on local ads for next to nothing.
Im currently shopping for a complete ultra high power complete sound system and tv with 2 x 12 inchs sub woofers for a big room. I decided to look for the latest stuff at amazon.com or wallmart.com or even best buy.ca , and it cost no more than 900$ up to 1100$
for a car audio system and home 12v power supply.
For a suggestion, buy a brand new digital car monobloc amp with a 12 volt power supply. It cost only 89$ for the new amp and 80$ for the 12 volts power supply and 25$ for the condensor. Some impressive brand I discovered yesterday was boss audio and the nice thing is that there is many other brand for the same price, infinity, kicker, pioneer, Rockford fosgate, pyramid, sound x stream, Rockville, All these brand utilize the latest digital circuitry that cost almost nothing to produce. Car audio is made using better technology because it is a tough market to compete in. Usually home audio is just beautiful looking furniture only and I decided to buy
car specification electronics. Look I have a home tv antenna that almost not work at all.. A lot of people buy mobile miniature cellphones with a small battery and receive and emit digital signals everywhere without problems.