Sally,
I'm not sure what you're hoping to achieve with this purchase. Sure, the 300D was rather dated, but in terms of your creativity and artistic ability, how do you think it will improve things by changing? Having already sold your 300D, I guess you have to replace it.
You can get a 400D for £300, see this link:
http://www.cameraworld.co.uk/ViewPro...UBCAT_CODE=149
I've used Cameraworld a few times as they are relatively local and can vouch for them.
Duncan