In the workplace, it is nearly always advisable to buy a laser printer. Printers are easy to share on a small network and a laser printer will be able to handle more volume at a considerably lower price. The cost of owning a printer is not so much in its purchase price, but in the consumables cost for each print. Add this to the purchase price to get the total cost of ownership and divide it by the number of sheets the manufacturer claims you will get from one set of consumables at say 5% coverage (normally a printed page of text).
Don't want the pain of working all this out? There are a number of websites which will do it for you. Try www.printware.co.uk who also have a handy printer finder.
A reasonable small/home office laser printer will cost less than £100 and will normally print 2000 sheets of A4 with the existing toner. A normal inkjet printer may cost £45 but will only print 200 sheets of A4 with the supplied ink cartridges.
For standard colour printing it is also now more cost effective to purchase a colour laser printer. Same criteria as above applies, but a fairly heavy duty office colour printer may cost in the region of £550. Check costs per copy again.
Duplex (printing on both sides) units are now commonly available on a number of printers and can substanitally reduce paper costs. Having a network port can allow all computers on a network to share one printer without having a specific computer turned on.
An inkjet printer comes into its own if you have a need to print glossy photograph style images (but check the prices at ASDA/your local supermarket, or for larger prints check out companies such as photobox). Inevitably and more often than you might imagine, the DIY approach with your own printer results in having to print an image more than once...