I have this one
http://www.medisana.com/en/New+products ... nitor.html
I was perfectly happy with it because you can connect it on your computer / iPhone / iPad (all at the same time) You'll find all the details on the link.
Now I dont use it anymore as Baby is now a Todler and sleeps hapillly through the night (thank Goodness!). price is £25
Let me know if you want more info, you are welcome to come and see how it works. We are in Rowditch Lane, SW11