Easier than mucking around with MOSFETs
I found this: http://uk.rs-online.com/web/p/darlington-transistor/0162795/
Basically it has 8 channels and each of those can continuously source 150mA at up to 50V. This means I can drive four 2-aspect Berko signals from one £2.15 IC. This is good.
Answers on a postcard (or in the comments) if you know the difference between a 2981 and a 2982. shrug
The Allegro UDN2981A-T appears to be the same as the Micrel MIC2981, in case you find that in stock instead. If you're doing things on breadboard, like me, you'll want the DIP package, not the surface mount ones.