I would pass on this particular machine and its two common sisters. It was made subsequent to the 206 and was the precursor to the 319.
They all take a 206x1 needle and when you can find them, they only come in two or three sizes. (14 and 16, I think) Naturally, they are also a lot more expensive than the "standard" 15x1 needle.
Some people have re-timed these machines to work with a 15x1 needle and the bobbin cases are often chewed up and destroyed because of it.
The 306 is kind of a clunky behemoth - the 319 is interesting for the "typewriter keys" that select the stitches, but I wouldn't even buy one of those. There are a lot more machines that are just as capable and don't require special needles. :)
On the other hand, if the machine appeals to you, you don't need any more reason than that to buy it - especially at that price. :)