Tom, I know they're old, but keep an eye out for Mission 760i. They're good through the midrange, deep bass is missing a little, but they're often on ebay for ~£25 buy it now.
Sometimes, they've been thrashed. Look for dust circles in the speaker cloth. Avoid those where possible. Apart from that, sometimes the tweeters are a bit quiet. Lowering the value of the series resistor sorts that out. Some experimentation will be needed, but the results are brilliant.
Chris