The dongle's now $35-$40 and trivially easy to use - basically, you plug it in. I don't remember even loading software in Panther with it - I think it just worked.
Any internal version's going to be more expensive - it's $50 BTO, and I'm sure more to have it installed afterward, and you need to use the antenna with the G5, so there's no huge plus to it. I've got the dongle on my 20" ACD, and it works quite well. Nice range, no problems.