Is it his absolute hearts desire? Because (sorry, I know you weren't asking for opinions but thought I'd put my 2p worth in anyway because it's such a massive important purchase!) I've always thought the battery operated vehicles are a bit lacking in play value tbh, especially considering how expensive they are. I think quite a few kids might lose interest pretty quickly once the initial wow/novelty factor wears off and there aren't that many places suitable to ride them. They also tend (quite rightly, for safety reasons) to go slower than the average pushbike so not always as good as they look for kids who love to bomb about at speed. But if he is a motorbike fiend who's always wanted one that's completely different, of course. Hope he has a wonderful birthday.
I got my ds one last week for his birthday, its from tesco and was £109.99 and it is fab. Sorry dont know how to do a link but its on their website. Ds loves it, he is 3 but goes from age 3 to 7, my dd goes on it and she is 6 .5 and its fine so would last a few years.