My Brother-in-law bought one of the weber wireless probes at Target, mistakingly thinking it was the same one that I use (I use a Maverick ET-7)
He fried his probes within a day of using it. Countless reviewers on amazon blast the thing for frying probes too easily and generally being a POS. (Maybe they used to be good, but switched manufacturers?)
YMMV, but from what I've heard there is a high defect rate on them.
Other probes - like the Maverick - can be had for similar price if you buy them online. I've never fried a maverick probe, but if I ever do - (my unit has two probes) I can just mail them my fried probe and they will mail me back a new one.
If you do get one and it works well, let me know - They are readily available and pretty cheap ($30). I wouldn't mind picking one up when I find myself 500 miles away from my grilling stuff and asked to cook a turkey for Christmas dinner (That happened to me this year... you never know how much you love your grill accessories until you are put in front of a grill without them)