If you're competent to do so, and a touch adventurous, I've made a power lead in the past which runs off an internal hard drive molex connector.
You would need the correct fitting DC power plug to fit the drive - but you can sometimes get these in a shop that sells smaller transformers. And or course you need to know which pins to use on the molex.
Don't be tempted to buy a "standard transformer" from an electrical shop. Their power outputs are virtually unregulated, and you would find it almost impossible to get one that can supply 1amp.
I have a Zip 100 that I used on my Old system Win '98 it hadn't a seperate power supply it used the computers I now use it on a new computer XP Home and use a Belkin 4 Port Hub and run it from that. If you have USB Ports buy a 4 Port Hub and run it from that, Much Cheaper!