I'm pretty sure that a suitable replacement for the tweeters could be found.
As for your sub HA, if it's the UFW-10 the drop in replacement is the Dayton Audio plate amp...
http://www.parts-express.com/pe/showdetl.cfm?Partnumber=300-804
It doesn't have as much power, but people have been having great success with it, as have I with both of my UFW-10s. The original amp, and it's later replacement from AV123 were pure crap.
The drivers are quite good though, and they're worth the few minutes required to replace the amps.