Before you spend any money on that bike, what wheels are on there? If they are crappy wheels and you start breaking a spoke every day you might wish you had just opted for a used mountain bike instead.
Personally, I think it's worth the money to get a real tour bike, but that money wouldn't be a problem for me, and I totally understand trying to work with what you have - just try to make sure in advance that it won't be a total money pit.