$100 challenge!

A friend of mine has a pair of Precision Acoustics HD45 tower speakers and is looking for an upgrade.

The speakers can be found here: (Precision Acoustics 2-Way Tower Speaker (HD45) - Single Speaker : Tower Speakers - Best Buy Canada)

He has a budget of about $100 Canadian and is interested in building a pair of compact bookshelves.

Of course were not expecting to be able to trump the HD45's in volume, as they use 4 x 5.25 woofers per speaker, however we would like to take them in sound quality (I know, broad term) and bass extension. The set he has used to be mine so I am very familiar with the sound. They would be lucky to hit 50hz, and I'm fairly simple they used a simple crossover that had all 4 woofers seeing identical signals. Vocals sound a bit muddled, and they break up quickly at med-high volumes.

Listening levels do not need to get very loud as he lives in an apartment.

We were looking at a simple 3" full range crossed to a used 8-10" ht subwoofer. We also thought about a decent 4" full range without subwoofer support. I had a hard time finding any 2-way designs that clocked in at under $100 shipped.

So, this being said, do you think a small, affordable full range or 2 way with great sound and decent extension (at mid-low volumes!) is achievable for around or under $100?
I'd see if you can get some used Behringer passive monitors: I've heard the B2031P (replaced my old speakers), and the B2030A. Both were good, full stop. When you consider the price of the things, they're fantastic.

I got mine for £110 delivered. An 8"+tweeter monitor isn't exactly compact, but I'm willing to bet they'll leave anything that can be DIY'd new for £100 for dead: each Seas tweeter costs ~£40: Behringer have massive economies of scale in their favour, making it incredibly difficult to compete at that level.