Actually It doesn't exists a universal browser PUBLIC
exploit, but they exist many many bugs for each browser (ie, firefox, opera, netscape, noone it's perfect!).
So I can write for you a webpage that first check the browser you are using and then redirect to a Internet Explorer exploit page if you use it or to a Firefox exploit page containg your own trojan for just 40usd !!
If you want the exploit page + a private trojan I can sell it for 60usd !!
Note that the os may be checked too, so you can redirect to a windows trojaned page or a linux one! But this may cost you more...
If you are interested on buyin private exploits (for any application remote or local) or malwares (virus, worm, trojan, keylogger, rootkits) for any architecture just contact me!!