Your only other option is to buy some used and pirate the parts you need. Maybe you can find a sub on ebay with a bad amp, or an ADP with a beat-up cabinet or blown woofer.
You can use an aftermarket driver in a sub much easier than you can on a full range speaker. If all else fails on the PS1000, we can look at alternatives. You need a Paradigm tweeter and only a Paradigm tweeter.