Did you find out about a warranty before you bought it from them?
My opinion is that, if it definitely was a faulty seal from Alpine, then they should provide some sort of compensation for fixing the problem.
I would like to state that most of us did NOT have a problem with our kits, so implying that the kit not being "bolt on" isn't really fair. For the price and the amount of assembly already done I believe it is a good deal. Had it been less assembled it may have been more costly to have a shop do the work for you, even though YOU may have been able to avoid your current problems. Again, most of us didn't have these problems with our kits. ***** happens sometimes, you know?
Personally, I would say they owe you some sort of compensation for what ever happens with the leaky seal.