Sushi, as far as the amp goes, it is a 30x4 Alpine - circa 1989. It fit perfectly under the passenger seat. Nothing too wild, but it is the family bus. When I was younger, I had all maner of "cheap" amps, and ALL of them failed in a glory of smoke and stench. (Although, that was 18 years ago - I was a teen, and had no concept of clipping and distortion. As long as it was loud......) I'm sure that a cheaper amp should be fine as long as YOU can't tell the difference in sound. As far as longevity, it shouldn't suffer the abuse my old ones did, so you should be fine.
Once I turned 20, I was able to afford my first Alpine amp. It played cleaner, louder, and was absolutely bullet proof. In fact, I have 5 Alpine amps in total (not in the van), and all of them are over 12 years old.
The cheaper brands are also notorious with their stratospheric power claims. Check the fuse rating and do the math. I've seen amps claim 1000 watts and have a 20 amp fuse! Sorry, not sure what they were smoking when they rated it. My Alpine with its claimed 120 watts has TWO 20 amp fuses and a 3 amp. I don't think it's bragging.
