These crimpers look like a knock off, but have good reviews. The genuine Platinum Tools version are atleast double the price (when I last looked/bought mine)
-- Edit
These are the top of the line EZ-RJ45 crimps. But they're expensive and only appear to be available from the USA at the moment.
It depends how many you need to do. Ratchet type crimpers are great, as they reduce hand strain when you have 50 to do, but for a few around the house, the basic ones are fine once you get the hang of it. I've got a few cheapo ones in various tool kits and a ratchet one I "borrowed" from work some years ago. My failure rate is about the same for both types!
The important bit is getting the right plug for the cable...