Set up an office network. Have a NW share for each user on a server. Get users to use the shared drives for work files, then backup the shared drives.
Budget is your only limitation but should be governed by your knowledge of how important your data is to you.
Could your business survive the loss of 1 day, 1 week, 1 years data?
Do want to use offsite storage in case of site loss?
Is there someone who will ensure success of backups each morning?
If anyones got private files on their own PCs they wanna back up tell them to do it themselves via USB key or CD burning but you're not responsible for them.
edit: Post crossed with dearg dooms who raises the same points.