Viking just came out with the Ruby Deluxe so it might be a good time to check the dealers so see what gently used Rubies or Topaz's they have on sale. The Deluxe is awesome as is the Ruby; which I got used only 7hrs but got the warranty and all. I've been using it for a yr and love it. I'm addicted!!!!
Make sure you get good customer support from Viking rep and classes. Get the one with the biggest hoop you can afford. I never use my 4x4 and don't even have a 5 x 7. I like using the biggest one that I have and putting more than one design on it at a time. The Vikings are great; not finicky about what thread you use and mine automatically adjust the tension. I've honestly never touched my tension since I got it. I could rave all day but obviously you know about the Vikings. If you can go up to a Ruby you'll find it has a lot of advantages over the Topaz; which is a great machine.