I'm a confirmed Bernina lover, so would always go with the used Bernina before just about anything else (unless it was a new Bernina, lol!).
A quick check on Ebay has a couple currently for sale; one is a "buy it now" auction listed for $700 and another for $575. In completed sales, there are also two: One sold for $504 and the other for $465. All of these have shipping added to the price - in the case of the least expensive ($465), another $75.
I think you got a great machine at a pretty good price! The ones I currently have are the 153QE (which I purchased new almost 12 years ago - still runs as well and stitches as beautifully as it did then) and a 240, which I bought for classes, retreats and guild sewing days.
There have been many threads here asking for advice on buying sewing machines for (whatever price range), usually people who do not want to spend thousands but want a good machine. Pretty much across the board, the responses are to look for a good quality used machine - like a Bernina.