Viking 500
I also have a Viking 500....have had it for more than 15 years. It has been very reliable, never has been serviced, and has a lot of stitches for a machine from that period of time. I've looked at the newer Sapphires with the larger throat, but just can't spend the money right now. The 500 is a little heavy to carry around, but I think that's because of what it's made of....not a lot of plastic parts. Bottom line? I think that they simply don't make them like they used to.
If you can test out the 500 before you buy it, great. If it's in good working condition, I don't think you'll regret your purchase.